Fix static analyzer warnings

This file had multiple warnings of the shape

art/runtime/jni_internal.cc: warning: Initialized va_list 'ap' is leaked

since CHECK_NON_NULL_ARGUMENT returns, rather than aborting the program.

Bug: 32619234
Test: test-art-host. Rebuilt ART with the analyzer to verify that these
issues are gone.

Change-Id: I40e1a839009246f919687278ac1d912bfb2f52ac