Simplify JEMALLOC_ATTR_* macros to become JEMALLOC_ATTR().

Use JEMALLOC_ATTR(tls_model("initial-exec)) instead of -ftls-model=initial-exec
so that libjemalloc_pic.a can be directly linked into another library without
needing linker options changes.

Add attributes to malloc, calloc, and posix_memalign, for compatibility with
glibc's declarations.

Add function prototypes for the standard malloc(3) API.
diff --git a/jemalloc/configure.ac b/jemalloc/configure.ac
index 0a32ac8..215131a 100644
--- a/jemalloc/configure.ac
+++ b/jemalloc/configure.ac
@@ -94,7 +94,6 @@
   JE_CFLAGS_APPEND([-pipe])
   JE_CFLAGS_APPEND([-g3])
   JE_CFLAGS_APPEND([-march=native])
-  JE_CFLAGS_APPEND([-ftls-model=initial-exec])
 fi
 dnl Append EXTRA_CFLAGS to CFLAGS, if defined.
 if test "x$EXTRA_CFLAGS" != "x" ; then
@@ -152,9 +151,7 @@
               [],
               [attribute])
 if test "x${attribute}" = "xyes" ; then
-  AC_DEFINE_UNQUOTED([JEMALLOC_UNUSED], [__attribute__((unused))])
-else
-  AC_DEFINE_UNQUOTED([JEMALLOC_UNUSED], [])
+  AC_DEFINE([JEMALLOC_HAVE_ATTR], [ ])
 fi
 
 dnl Platform-specific settings.  abi and RPATH can probably be determined