[LockFileManager] Reduce lock timeout

Go back to behavior pre-r231309 and reduce the timeout from 8 to ~1.5
min now that we have (a) PCMCache mechanism (r298165) and (b) timeout
that doesn't cause a failure, but actually build the module (r298175).

rdar://problem/30297862

llvm-svn: 298176
diff --git a/llvm/lib/Support/LockFileManager.cpp b/llvm/lib/Support/LockFileManager.cpp
index 444aaa3..8be9879 100644
--- a/llvm/lib/Support/LockFileManager.cpp
+++ b/llvm/lib/Support/LockFileManager.cpp
@@ -304,9 +304,9 @@
   Interval.tv_sec = 0;
   Interval.tv_nsec = 1000000;
 #endif
-  // Don't wait more than five minutes per iteration. Total timeout for the file
-  // to appear is ~8.5 mins.
-  const unsigned MaxSeconds = 5*60;
+  // Don't wait more than 40s per iteration. Total timeout for the file
+  // to appear is ~1.5 minutes.
+  const unsigned MaxSeconds = 40;
   do {
     // Sleep for the designated interval, to allow the owning process time to
     // finish up and remove the lock file.