ci_build.sh: allow CI workers to say if they have functional libgd (for the current compiler/ABI version) so whether it should not be required

Author: jimklimov

ci_build.sh

@@ -200,7 +200,7 @@ default|default-alldrv|default-all-errors|default-spellcheck|default-shellcheck|
             CONFIG_OPTS+=("--with-doc=skip")
             # Enable as many binaries to build as current worker setup allows
             CONFIG_OPTS+=("--with-all=auto")
-            if [[ "$TRAVIS_OS_NAME" != "windows" ]] && [[ "$TRAVIS_OS_NAME" != "freebsd" ]] ; then
+            if [[ "$TRAVIS_OS_NAME" != "windows" ]] && [[ "$TRAVIS_OS_NAME" != "freebsd" ]] && [ "${BUILD_LIBGD_CGI-}" != "auto" ] ; then
                 # Currently --with-all implies this, but better be sure to
                 # really build everything we can to be certain it builds:
                 if pkg-config --exists libgd || pkg-config --exists libgd2 || pkg-config --exists libgd3 || pkg-config --exists gdlib ; then