Fix compilation warnings reported by gcc -Wsign-compare

* configure.ac (gl_WARN_ADD): Add -Wsign-compare.
* defs.h (struct tcb): Change 'currpers' type to unsigned.
(struct xlat): Change 'val' type to unsigned
(signame): Add 'const' qualifier to its argument.
(xlookup, printxval): Add 'const' qualifier to the 2nd argument and
change its type to unsigned.
(printpathn): Change the 3rd argument type to unsigned.
(ioctl_lookup): Change 1st argument type to unsigned.
* count.c (call_summary_pers, call_summary): Change 'i' type to unsigned.
* file.c (print_xattr_list): Fix comparisons between signed and unsigned
long values.
* ioctl.c (compare): Fix cast.
(ioctl_lookup): Change 1st argument type to to unsigned.
(ioctl_next_match): Change 'code' type to unsigned.
* mem.c (sys_move_pages): Change 'i' type to unsigned.
* mtd.c (mtd_ioctl): Change 'i' and 'j' types to unsigned.
Print 'i' using %u format string.
* process.c (sys_prctl): Change 'i' type to unsigned.
(printargv): Change 'n' type to unsigned.
(sys_ptrace): Change 'addr' type to unsigned.
* scsi.c (print_sg_io_buffer): Add 'const' qualifier to 'len' argument
and change its type to unsigned.  Change 'i' and 'allocated' types
to unsigned.
* signal.c (signame): Add 'const' qualifier to its argument.
Fix comparisons between signed and unsigned values.
(sprintsigmask_n, printsiginfo): Fix comparisons between signed and
unsigned values.
* sock.c (sock_ioctl): Change 'i' and 'nifra' types to unsigned.
* strace.c (expand_tcbtab, alloctcb): Change 'i' type to unsigned.
(detach): Change 'sig' type to unsigned.
(startup_attach): Change 'tcbi' type to unsigned.
(startup_child): Change 'm', 'n', and 'len' types to unsigned.
(init): Use new variable to iterate 'tcbtab'.
(pid2tcb): Change 'i' type to unsigned.
(cleanup): Change 'i' and 'sig' types to unsigned.
* syscall.c (update_personality): Change 'personality' argument type
to unsigned.
(struct qual_options): Change 'bitflag' type to unsigned.
(reallocate_qual): Add 'const' qualifier to its argument and change its
type to unsigned.
(qualify_one): Change 'n' and 'bitflag' arguments types to unsigned.
Add 'const' qualifier to 'n', 'not', and 'pers' arguments.
Change 'p' type to signed int.
(qual_syscall): Change 'bitflag' argument type to unsigned.
Add 'const' qualifier to 'bitflag' and 'not' arguments.
Change 'p' type to signed int.
(qual_signal): Change 'bitflag' argument type to unsigned.
Add 'const' qualifier to 'bitflag' and 'not' arguments.
Change 'i' type to unsigned.
(qual_desc): Change 'bitflag' argument type to unsigned.
Add 'const' qualifier to 'bitflag' and 'not' arguments.
(qualify): Change 'i' type to unsigned.
(get_scno): Change 'currpers' type to unsigned.
Fix a comparison between signed and unsigned values.
* system.c (sys_sysctl): Change 'cnt' and 'max_cnt' types to unsigned.
Fix comparisons between signed and unsigned values.
* util.c (xlookup, printxval): Add 'const' qualifier to 'val' argument
and change its type to unsigned.
(printuid): Fix a comparison between signed and unsigned values.
(printpathn): Change 'n' argument type to unsigned.
(printstr): Change 'size' type to unsigned.
Fix a comparison between signed and unsigned values.
(setbpt): Change 'i' type to unsigned.
* net.c (printsock): Silence a compilation warning.
* reboot.c (sys_reboot): Likewise.
diff --git a/defs.h b/defs.h
index 625cac6..396e519 100644
--- a/defs.h
+++ b/defs.h
@@ -414,7 +414,7 @@
 #endif
 	long u_rval;		/* Return value */
 #if SUPPORTED_PERSONALITIES > 1
-	int currpers;		/* Personality at the time of scno update */
+	unsigned int currpers;	/* Personality at the time of scno update */
 #endif
 	int curcol;		/* Output column for this process */
 	FILE *outf;		/* Output file for this process */
@@ -508,7 +508,7 @@
 #define filtered(tcp)	((tcp)->flags & TCB_FILTERED)
 
 struct xlat {
-	int val;
+	unsigned int val;
 	const char *str;
 };
 #define XLAT(x) { x, #x }
@@ -642,12 +642,12 @@
 extern int setbpt(struct tcb *);
 extern int clearbpt(struct tcb *);
 
-extern const char *signame(int);
+extern const char *signame(const int);
 extern void pathtrace_select(const char *);
 extern int pathtrace_match(struct tcb *);
 extern int getfdpath(struct tcb *, int, char *, unsigned);
 
-extern const char *xlookup(const struct xlat *, int);
+extern const char *xlookup(const struct xlat *, const unsigned int);
 
 extern int string_to_uint(const char *str);
 extern int string_quote(const char *, char *, long, int);
@@ -665,7 +665,7 @@
 #endif
 extern int printllval(struct tcb *, const char *, int);
 
-extern void printxval(const struct xlat *, int, const char *);
+extern void printxval(const struct xlat *, const unsigned int, const char *);
 extern int printargs(struct tcb *);
 extern int printargs_lu(struct tcb *);
 extern int printargs_ld(struct tcb *);
@@ -678,7 +678,7 @@
 extern void printnum(struct tcb *, long, const char *);
 extern void printnum_int(struct tcb *, long, const char *);
 extern void printpath(struct tcb *, long);
-extern void printpathn(struct tcb *, long, int);
+extern void printpathn(struct tcb *, long, unsigned int);
 #define TIMESPEC_TEXT_BUFSIZE (sizeof(long)*3 * 2 + sizeof("{%u, %u}"))
 #define TIMEVAL_TEXT_BUFSIZE  TIMESPEC_TEXT_BUFSIZE
 extern void printtv_bitness(struct tcb *, long, enum bitness_t, int);
@@ -710,7 +710,7 @@
 extern const char *sprint_open_modes(mode_t);
 extern void print_loff_t(struct tcb *, long);
 
-extern const struct_ioctlent *ioctl_lookup(long);
+extern const struct_ioctlent *ioctl_lookup(unsigned long);
 extern const struct_ioctlent *ioctl_next_match(const struct_ioctlent *);
 extern int ioctl_decode(struct tcb *, long, long);
 extern int term_ioctl(struct tcb *, long, long);