build: check FIPS option value in node.gyp

openssl_is_fips is always the string "true" or "false", so testing
whether it is non-empty always adds OPENSSL_FIPS to mkssldef. Add the
define only when FIPS was requested.

Signed-off-by: Filip Skokan <panva.ip@gmail.com>
PR-URL: #64982
Reviewed-By: Richard Lau <richard.lau@ibm.com>
Reviewed-By: Aviv Keller <me@aviv.sh>

Author: panva

node.gyp

@@ -1051,7 +1051,7 @@
             ],
           },
           'conditions': [
-            ['openssl_is_fips!=""', {
+            ['openssl_is_fips=="true"', {
               'variables': { 'mkssldef_flags': ['-DOPENSSL_FIPS'] },
             }],
           ],