Check for warnings in a bunch of the linker invocations, and add one
with both -static-libgcc and -static on the commandline.

Fix a warning in the latter case due to a backwards short circuiting ||
operator in the driver. No real functionality changed here, just allows
the driver to properly consume -static-libgcc when -static is also
specified.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@176429 91177308-0d34-0410-b5e6-96231b3b80d8