Handle errors during pthread calls

Summary: Release locks before calling exit.

Test Plan: Force errors in debugger and verify correctness

Reviewers: igor, yhchiang, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D30423

util/env_posix.cc

@@ -1068,7 +1068,7 @@ class PosixFileLock : public FileLock {
 void PthreadCall(const char* label, int result) {
   if (result != 0) {
     fprintf(stderr, "pthread %s: %s\n", label, strerror(result));
-    exit(1);
+    abort();
   }
 }