glibc: add patch for CVE-2019-19126

including patch in-repo as it needs modification to remove the changes to
NEWS but fetchpatch doesn't work here

pkgs/development/libraries/glibc/2.27-CVE-2019-19126.patch

@@ -0,0 +1,18 @@
+Adapted from https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=patch;h=4d5cfeb510125345cb41431afc9022492994cffa, omitting changes to NEWS
+diff --git a/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h b/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
+index 1943691..ac694c0 100644
+--- a/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
++++ b/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
+@@ -31,7 +31,8 @@
+    environment variable, LD_PREFER_MAP_32BIT_EXEC.  */
+ #define EXTRA_LD_ENVVARS \
+   case 21:								  \
+-    if (memcmp (envline, "PREFER_MAP_32BIT_EXEC", 21) == 0)		  \
++    if (!__libc_enable_secure						  \
++	&& memcmp (envline, "PREFER_MAP_32BIT_EXEC", 21) == 0)		  \
+       GLRO(dl_x86_cpu_features).feature[index_arch_Prefer_MAP_32BIT_EXEC] \
+ 	|= bit_arch_Prefer_MAP_32BIT_EXEC;				  \
+     break;
+-- 
+2.9.3
+

pkgs/development/libraries/glibc/common.nix

@@ -98,7 +98,10 @@ stdenv.mkDerivation ({
       # https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f51c8367685dc888a02f7304c729ed5277904aff
       ./CVE-2018-11237.patch
     ]
-    ++ lib.optional stdenv.isx86_64 ./fix-x64-abi.patch
+    ++ lib.optionals stdenv.isx86_64 [
+      ./fix-x64-abi.patch
+      ./2.27-CVE-2019-19126.patch
+    ]
     ++ lib.optional stdenv.hostPlatform.isMusl ./fix-rpc-types-musl-conflicts.patch
     ++ lib.optional stdenv.buildPlatform.isDarwin ./darwin-cross-build.patch