gcc49: fix build w/glibc-2.31

The same `libsanitizer` problem as in llvm<10 and newer GCCs.

https://hydra.nixos.org/build/122902814
https://hydra.nixos.org/build/122903349

pkgs/development/compilers/gcc/4.9/default.nix

@@ -63,6 +63,7 @@ let majorVersion = "4";
 
     patches =
       [ ../use-source-date-epoch.patch ../parallel-bconfig.patch ./parallel-strsignal.patch
+        ./libsanitizer.patch
         (fetchpatch {
           name = "avoid-ustat-glibc-2.28.patch";
           url = "https://gitweb.gentoo.org/proj/gcc-patches.git/plain/4.9.4/gentoo/100_all_avoid-ustat-glibc-2.28.patch?id=55fcb515620a8f7d3bb77eba938aa0fcf0d67c96";

pkgs/development/compilers/gcc/4.9/libsanitizer.patch

@@ -0,0 +1,24 @@
+diff --git a/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.h b/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.h
+index aec950454..5bda9b3a3 100644
+--- a/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.h
++++ b/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.h
+@@ -156,18 +156,13 @@ namespace __sanitizer {
+ #elif defined(__sparc__)
+ # if defined(__arch64__)
+     unsigned mode;
+-    unsigned short __pad1;
+-# else
+-    unsigned short __pad1;
+-    unsigned short mode;
+     unsigned short __pad2;
+ # endif
+     unsigned short __seq;
+     unsigned long long __unused1;
+     unsigned long long __unused2;
+ #else
+-    unsigned short mode;
+-    unsigned short __pad1;
++    unsigned int mode;
+     unsigned short __seq;
+     unsigned short __pad2;
+ #if defined(__x86_64__) && !defined(_LP64)