8196990: Resolve disabled warnings for libjli

Initialized uninitialzed data to avoid maybe-uninitialized warnings from gcc

Reviewed-by: jlaskey

make/lib/CoreLibraries.gmk

@@ -298,7 +298,6 @@ $(eval $(call SetupJdkLibrary, BUILD_LIBJLI, \
     EXTRA_FILES := $(LIBJLI_EXTRA_FILES), \
     OPTIMIZATION := HIGH, \
     CFLAGS := $(LIBJLI_CFLAGS), \
-    DISABLED_WARNINGS_gcc := maybe-uninitialized, \
     DISABLED_WARNINGS_solstudio := \
         E_ASM_DISABLES_OPTIMIZATION \
         E_STATEMENT_NOT_REACHED, \

src/java.base/share/native/libjli/args.c

@@ -305,6 +305,8 @@ static JLI_List readArgFile(FILE *file) {
 
     ctx.state = FIND_NEXT;
     ctx.parts = JLI_List_new(4);
+    // initialize to avoid -Werror=maybe-uninitialized issues from gcc 7.3 onwards.
+    ctx.quote_char = '"';
 
     /* arbitrarily pick 8, seems to be a reasonable number of arguments */
     rv = JLI_List_new(8);