8272332: --with-harfbuzz=system doesn't add -lharfbuzz after JDK-8255790

Backport-of: d38b31438dd4730ee2149c02277d60c35b9d7d81

Author: jerboaa

make/modules/java.desktop/lib/Awt2dLibraries.gmk

@@ -435,7 +435,7 @@ endif
 
 ifeq ($(USE_EXTERNAL_HARFBUZZ), true)
    LIBFONTMANAGER_EXTRA_SRC =
-   BUILD_LIBFONTMANAGER_FONTLIB += $(LIBHARFBUZZ_LIBS)
+   BUILD_LIBFONTMANAGER_FONTLIB += $(HARFBUZZ_LIBS)
 else
    LIBFONTMANAGER_EXTRA_SRC = libharfbuzz