Flush gcda files before unlocking them

Summary: Fixes https://bugs.llvm.org/show_bug.cgi?id=35464.

Reviewers: zturner, rnk, void

Subscribers: sylvestre.ledru, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D40610

llvm-svn: 321702

compiler-rt/lib/profile/GCDAProfiling.c

@@ -459,6 +459,7 @@ void llvm_gcda_end_file() {
       unmap_file();
     }
 
+    fflush(output_file);
     lprofUnlockFd(fd);
     fclose(output_file);
     output_file = NULL;