This CL replaces the Clang 'c++-analyzer' Perl script with logic added to the Python wrapper script. This gives us the hooks we need to run analysis builds with "gomacc" (necessary for distributed builds) and gives us a convenient place to specify analyzer config flags which aren't exposed by scan-build.

Adds a warning suppression rule which prevents the analyzer from raising false positives from stdlib code (code w/namespace "std").

Other changes:
* Modify Goma portions of the GCC toolchain GNI to build paths to
  the Clang static analyzer.
* Create an exception for ASM tool invocations, which don't play
  well with the analysis command line flags.
* Removed 'scan-build' DEP.

BUG=687245
R=thakis@chromium.org,wez@chromium.org

Review-Url: https://codereview.chromium.org/2667853004
Cr-Commit-Position: refs/heads/master@{#456136}