Speculative fix for nullptr program in QueryProgramiv

It is reported that an increase crash rate is seen on M81.
This is a speculative fix based on that most crashes have calls from
GrGLProgramBuilder::checkLinkStatus.

Bug: chromium:991020
Change-Id: I549de9e0a0cccde8b9c68d706828963fe3f9bdf2
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2095596
Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Shrek Shao <shrekshao@google.com>
Commit-Queue: Shrek Shao <shrekshao@google.com>

src/libANGLE/queryutils.cpp

@@ -1195,7 +1195,7 @@ void QueryProgramiv(Context *context, const Program *program, GLenum pname, GLin
             *params = program->isFlaggedForDeletion();
             return;
         case GL_LINK_STATUS:
-            *params = program->isLinked();
+            *params = program ? program->isLinked() : false;
             return;
         case GL_COMPLETION_STATUS_KHR:
             if (context->isContextLost())