Support: Fix handling of args that begin with @ but aren't files

Command line arguments that begin with @ but aren't a path to an
existing file currently cause later @file arguments to be ignored.

Correctly skip over these arguments instead of trying to read a
non-existent file 20 times and giving up.

Since the problem manifests in the clang driver, the test is in that
repository.

Fixes rdar://problem/15590906

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196620 91177308-0d34-0410-b5e6-96231b3b80d8
Cache AllowAtInIdentifier as class variable in AsmLexer

This commit caches the value of the AllowAtInIdentifier variable as
a class variable in AsmLexer. We do this to avoid repeated MAI
queries and string comparisons each time we lex an identifier.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196622 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a narrowing warning due to a type mismatch (size_t vs uint64).

lib/Transforms/Instrumentation/AddressSanitizer.cpp:1405:36: error: non-constant-expression cannot be narrowed from type 'uint64_t' (aka 'unsigned long long') to 'size_t' (aka 'unsigned int') in initializer list [-Wc++11-narrowing]
    getAllocaSizeInBytes(AI),
    ^~~~~~~~~~~~~~~~~~~~~~~~

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196623 91177308-0d34-0410-b5e6-96231b3b80d8