nss: Disable Werror across all recipe types

We are seeing warnigs with gcc-10 even on target builds e.g.

| In file included from nsinstall.c:20:
| /usr/include/unistd.h:520:14: note: in a call to function ‘getcwd’ declared with attribute ‘write_only (1, 2)’
|   520 | extern char *getcwd (char *__buf, size_t __size) __THROW __wur
|       |              ^~~~~~
| nsinstall.c:70:16: error: argument 1 is null but the corresponding size argument 2 value is 4096 [-Werror=nonnull]
|    70 | #define GETCWD getcwd
|       |                ^
| nsinstall.c:246:13: note: in expansion of macro ‘GETCWD’
|   246 |     todir = GETCWD(0, PATH_MAX);
|       |             ^~~~~~

Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-support/nss/nss_3.54.bb

@@ -58,7 +58,6 @@ do_configure_prepend_libc-musl () {
 do_compile_prepend_class-native() {
     export NSPR_INCLUDE_DIR=${STAGING_INCDIR_NATIVE}/nspr
     export NSPR_LIB_DIR=${STAGING_LIBDIR_NATIVE}
-    export NSS_ENABLE_WERROR=0
 }
 
 do_compile_prepend_class-nativesdk() {
@@ -72,6 +71,7 @@ do_compile_prepend_class-native() {
 
 do_compile() {
     export NSPR_INCLUDE_DIR=${STAGING_INCDIR}/nspr
+    export NSS_ENABLE_WERROR=0
 
     export CROSS_COMPILE=1
     export NATIVE_CC="${BUILD_CC}"