llvm-readobj: zero out timestamp in COFF auto-generated test files.

The timestamp meant these files changed with each invocation of
relocs.py, confusing matters when we add relocations and need to
update the tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215350 91177308-0d34-0410-b5e6-96231b3b80d8

test/tools/llvm-readobj/Inputs/relocs.py

@@ -327,6 +327,10 @@ def patchCoff(path, relocs):
 
   machine_type            = f.uint16()
   section_count           = f.uint16()
+
+  # Zero out timestamp to prevent churn when regenerating COFF files.
+  f.writeUInt32(0)
+
   f.seek(20)
   sections = [CoffSection(f) for idx in range(section_count)]