8027912: [macosx] Provide means to force the headful mode on OS X when running via ssh

Summary: Bypass AquaSession check if AWT_FORCE_HEADFUL env. variable is set to TRUE
Reviewed-by: anthony, art
Contributed-by: NDavid Dehaven <david.dehaven@oracle.com>

src/solaris/native/java/lang/java_props_macosx.c

@@ -106,6 +106,12 @@ char *setupMacOSXLocale(int cat) {
 }
 
 int isInAquaSession() {
+    // environment variable to bypass the aqua session check
+    char *ev = getenv("AWT_FORCE_HEADFUL");
+    if (ev && (strncasecmp(ev, "true", 4) == 0)) {
+        // if "true" then tell the caller we're in an Aqua session without actually checking
+        return 1;
+    }
     // Is the WindowServer available?
     SecuritySessionId session_id;
     SessionAttributeBits session_info;