Export gmock-spec-builders.

gmock.h is the umbrella header to be used for rest of the library, and it also
enables users to export certain details. This wasn't working for some interfaces
like EXPECT_CALL because gmock-spec-builders wasn't explicitly exported.

PiperOrigin-RevId: 576966583
Change-Id: Ie050430cf11384977cd95f4ed6e73235d6857057

googlemock/include/gmock/gmock.h

@@ -60,6 +60,7 @@
 #include "gmock/gmock-more-actions.h"  // IWYU pragma: export
 #include "gmock/gmock-more-matchers.h"  // IWYU pragma: export
 #include "gmock/gmock-nice-strict.h"  // IWYU pragma: export
+#include "gmock/gmock-spec-builders.h"  // IWYU pragma: export
 #include "gmock/internal/gmock-internal-utils.h"
 #include "gmock/internal/gmock-port.h"