Upgrade libm.

This brings us up to date with FreeBSD HEAD, fixes various bugs, unifies
the set of functions we support on ARM, MIPS, and x86, fixes "long double",
adds ISO C99 support, and adds basic unit tests.

It turns out that our "long double" functions have always been broken
for non-normal numbers. This patch fixes that by not using the upstream
implementations and just forwarding to the regular "double" implementation
instead (since "long double" on Android is just "double" anyway, which is
what BSD doesn't support).

All the tests pass on ARM, MIPS, and x86, plus glibc on x86-64.

Bug: 3169850
Bug: 8012787
Bug: https://code.google.com/p/android/issues/detail?id=6697
Change-Id: If0c343030959c24bfc50d4d21c9530052c581837

libc/include/sys/cdefs.h

@@ -177,6 +177,8 @@
 #define	__unused	/* delete */
 #endif
 
+#define __pure2 __attribute__((__const__)) /* Android-added: used by FreeBSD libm */
+
 #if __GNUC_PREREQ__(3, 1)
 #define	__used		__attribute__((__used__))
 #else
@@ -313,6 +315,12 @@
 #define __purefunc
 #endif
 
+#if __GNUC_PREREQ__(3, 1)
+#define __always_inline __attribute__((__always_inline__))
+#else
+#define __always_inline
+#endif
+
 /*
  * Macros for manipulating "link sets".  Link sets are arrays of pointers
  * to objects, which are gathered up by the linker.
@@ -510,4 +518,11 @@
 #define __BIONIC_FORTIFY_UNKNOWN_SIZE ((size_t) -1)
 #endif
 
+/* Android-added: for FreeBSD's libm. */
+#define __weak_reference(sym,alias) \
+    __asm__(".weak " #alias); \
+    __asm__(".equ "  #alias ", " #sym)
+#define __strong_reference(sym,aliassym) \
+    extern __typeof (sym) aliassym __attribute__ ((__alias__ (#sym)))
+
 #endif /* !_SYS_CDEFS_H_ */