Fix uninitialized fCurrProgramID in GrGLCreateNullInterface

TBR=bsalomon@google.com,robertphillips@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1817793002

Review URL: https://codereview.chromium.org/1817793002
1 file changed