[GCOV] Function counters are wrong when on one line

Summary:
After commit https://reviews.llvm.org/rL344228, the function definitions have a counter but when on one line the counter is wrong (e.g. void foo() { })
I added a test in: https://reviews.llvm.org/D53601

Reviewers: marco-c

Reviewed By: marco-c

Subscribers: llvm-commits, sylvestre.ledru

Differential Revision: https://reviews.llvm.org/D53600

llvm-svn: 345624