workflows/macos: add a job using gcc + debug + secure transport

.github/workflows/macos.yml

@@ -83,6 +83,9 @@ jobs:
           install: nghttp2
           configure: --enable-debug --with-secure-transport
           macosx-version-min: 10.8
+        - name: gcc SecureTransport
+          configure: CC=gcc-12 --enable-debug --with-secure-transport
+          macosx-version-min: 10.8
         - name: OpenSSL http2
           install: nghttp2 openssl
           configure: --enable-debug --with-openssl=/usr/local/opt/openssl