Stop gyp_chromium prior to mass DLL copies on error

Also fix last-modified-time comparison code to handle minor float
differences and thus correctly not copy identical files (for some
reason there appears to be a ~1e-07 diff between last-modified-time
of copied files...?).

BUG=603603
TEST=No more copy output from gyp_chromium when copied DLLs are already
there or gyp_rc != 0 :-)

Review URL: https://codereview.chromium.org/1890053004

Cr-Commit-Position: refs/heads/master@{#387911}

build/gyp_chromium.py

@@ -343,7 +343,7 @@ def main():
   # Off we go...
   gyp_rc = gyp.main(args)
 
-  if not use_analyzer:
+  if gyp_rc == 0 and not use_analyzer:
     vs2013_runtime_dll_dirs = vs_toolchain.SetEnvironmentAndGetRuntimeDllDirs()
     if vs2013_runtime_dll_dirs:
       x64_runtime, x86_runtime = vs2013_runtime_dll_dirs

build/vs_toolchain.py

@@ -153,12 +153,14 @@ def _VersionNumber():
 
 
 def _CopyRuntimeImpl(target, source, verbose=True):
-  """Copy |source| to |target| if it doesn't already exist or if it
-  needs to be updated.
+  """Copy |source| to |target| if it doesn't already exist or if it needs to be
+  updated (comparing last modified time as an approximate float match as for
+  some reason the values tend to differ by ~1e-07 despite being copies of the
+  same file... https://crbug.com/603603).
   """
   if (os.path.isdir(os.path.dirname(target)) and
       (not os.path.isfile(target) or
-      os.stat(target).st_mtime != os.stat(source).st_mtime)):
+       abs(os.stat(target).st_mtime - os.stat(source).st_mtime) >= 0.01)):
     if verbose:
       print 'Copying %s to %s...' % (source, target)
     if os.path.exists(target):
@@ -185,7 +187,6 @@ def _CopyRuntime2015(target_dir, source_dir, dll_pattern, suffix):
     source = os.path.join(source_dir, dll)
     _CopyRuntimeImpl(target, source)
   ucrt_src_dir = os.path.join(source_dir, 'api-ms-win-*.dll')
-  print 'Copying %s to %s...' % (ucrt_src_dir, target_dir)
   for ucrt_src_file in glob.glob(ucrt_src_dir):
     file_part = os.path.basename(ucrt_src_file)
     ucrt_dst_file = os.path.join(target_dir, file_part)