[PATCH][PR sanitizer/78532] Fix libsanitizer build failure on sparc64-linux-gnu.

[Maxim Ostapenko]

Hi,

this patch restores libsanitizer build on sparc64-linux-gnu with Glibc 
2.20+ on board.
I verified that this patch fixes the build error locally with Glibc 2.24.
Ok for mainline?
libsanitizer/ChangeLog:

2016-11-30  Maxim Ostapenko  <m.ostape...@samsung.com>

	PR sanitizer/78532
	* sanitizer_common/sanitizer_platform_limits_posix.h
	(__sanitizer_sigaction): Adjust for sparc targets and various Glibc
	versions.

diff --git a/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.h b/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.h
index d1a3051..066bf41 100644
--- a/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.h
+++ b/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.h
@@ -25,6 +25,10 @@
 # define GET_LINK_MAP_BY_DLOPEN_HANDLE(handle) ((link_map*)(handle))
 #endif  // !SANITIZER_FREEBSD
 
+#ifndef __GLIBC_PREREQ
+#define __GLIBC_PREREQ(x, y) 0
+#endif
+
 namespace __sanitizer {
   extern unsigned struct_utsname_sz;
   extern unsigned struct_stat_sz;
@@ -628,7 +632,14 @@ namespace __sanitizer {
 #endif
 #ifndef __mips__
 #if defined(__sparc__)
+#if __GLIBC_PREREQ (2, 20)
+    // On sparc glibc 2.19 and earlier sa_flags was unsigned long, and
+    // __glibc_reserved0 didn't exist.
+    int __glibc_reserved0;
+    int sa_flags;
+#else
     unsigned long sa_flags;
+#endif
 #else
     int sa_flags;
 #endif