gdb: pull upstream fix for gcc-12

Without the change the build fails as:

    sim/cr16/interp.c: In function 'lookup_hash':
    sim/cr16/interp.c:89:25: error:
      the comparison will always evaluate as 'true'
      for the address of 'mnimonic' will never be NULL [-Werror=address]
       89 |   if ((h->ops->mnimonic != NULL) &&
          |                         ^~

pkgs/development/tools/misc/gdb/default.nix

@@ -1,7 +1,7 @@
 { lib, stdenv, targetPackages
 
 # Build time
-, fetchurl, pkg-config, perl, texinfo, setupDebugInfoDirs, buildPackages
+, fetchurl, fetchpatch, pkg-config, perl, texinfo, setupDebugInfoDirs, buildPackages
 
 # Run time
 , ncurses, readline, gmp, mpfr, expat, libipt, zlib, dejagnu, sourceHighlight
@@ -41,6 +41,13 @@ stdenv.mkDerivation rec {
 
   patches = [
     ./debug-info-from-env.patch
+
+    # Pull upstream fix for gcc-12. Will be included in gdb-12.
+    (fetchpatch {
+      name = "gcc-12.patch";
+      url = "https://sourceware.org/git/?p=binutils-gdb.git;a=patch;h=e97436b1b789dcdb6ffb502263f4c86f8bc22996";
+      sha256 = "1mpgw6s9qgnwhwyg3hagc6vhqhvia0l1s8nr22bcahwqxi3wvzcw";
+    })
   ] ++ lib.optionals stdenv.isDarwin [
     ./darwin-target-match.patch
   ];