Cleanup after non-Linux code removal.

Conditions such as defined(LINUX) are always true now,
defined(FREEBSD) etc are always false.
When if directive has them as subexpressions, it can be simplified.
Another trivial changes here are fixes for directive indentation.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/syscall.c b/syscall.c
index 978c65a..b94ad65 100644
--- a/syscall.c
+++ b/syscall.c
@@ -60,14 +60,14 @@
 # undef pt_all_user_regs
 #endif
 
-#if defined (LINUX) && defined (SPARC64)
+#if defined(SPARC64)
 # undef PTRACE_GETREGS
 # define PTRACE_GETREGS PTRACE_GETREGS64
 # undef PTRACE_SETREGS
 # define PTRACE_SETREGS PTRACE_SETREGS64
-#endif /* LINUX && SPARC64 */
+#endif
 
-#if defined(LINUX) && defined(IA64)
+#if defined(IA64)
 # include <asm/ptrace_offsets.h>
 # include <asm/rse.h>
 #endif
@@ -523,7 +523,7 @@
 
 enum subcall_style { shift_style, deref_style, mask_style, door_style };
 
-#if !(defined(LINUX) && ( defined(ALPHA) || defined(MIPS) || defined(__ARM_EABI__) ))
+#if !(defined(ALPHA) || defined(MIPS) || defined(__ARM_EABI__))
 
 static void
 decode_subcall(struct tcb *tcp, int subcall, int nsubcalls, enum subcall_style style)
@@ -1206,9 +1206,9 @@
 	   )
 		return internal_fork(tcp);
 
-#if defined SUNOS4 || (defined LINUX && defined TCB_WAITEXECVE)
+#if defined(TCB_WAITEXECVE)
 	if (   sys_execve == func
-# if defined(SPARC) || defined(SPARC64) || defined(SUNOS4)
+# if defined(SPARC) || defined(SPARC64)
 	    || sys_execv == func
 # endif
 	   )