gcc: disable libsanitizer for uclibc

libsanitizer requires header files which are not present in uclibc.

Also, libsanitizer is disabled with uclibc for buildroot[1] and
openwrt[2].

[1]: https://git.busybox.net/buildroot/commit/?id=554e29e267e6b36a0fd78c82cbad2c82d939eb7f
[2]: https://gitlab.labs.nic.cz/turris/openwrt/commit/5f372a8ca08de4b2253b87253ca7762450e5641f

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

@@ -189,6 +189,9 @@ let version = "4.9.3";
             # To keep ABI compatibility with upstream mingw-w64
             " --enable-fully-dynamic-string"
             else (if cross.libc == "uclibc" then
+              # libsanitizer requires netrom/netrom.h which is not
+              # available in uclibc.
+              " --disable-libsanitizer" +
               # In uclibc cases, libgomp needs an additional '-ldl'
               # and as I don't know how to pass it, I disable libgomp.
               " --disable-libgomp" else "") +

pkgs/development/compilers/gcc/5/default.nix

@@ -189,6 +189,9 @@ let version = "5.4.0";
             # To keep ABI compatibility with upstream mingw-w64
             " --enable-fully-dynamic-string"
             else (if cross.libc == "uclibc" then
+              # libsanitizer requires netrom/netrom.h which is not
+              # available in uclibc.
+              " --disable-libsanitizer" +
               # In uclibc cases, libgomp needs an additional '-ldl'
               # and as I don't know how to pass it, I disable libgomp.
               " --disable-libgomp" else "") +

pkgs/development/compilers/gcc/6/default.nix

@@ -188,6 +188,9 @@ let version = "6.1.0";
             # To keep ABI compatibility with upstream mingw-w64
             " --enable-fully-dynamic-string"
             else (if cross.libc == "uclibc" then
+              # libsanitizer requires netrom/netrom.h which is not
+              # available in uclibc.
+              " --disable-libsanitizer" +
               # In uclibc cases, libgomp needs an additional '-ldl'
               # and as I don't know how to pass it, I disable libgomp.
               " --disable-libgomp" else "") +