Remove some low hanging fruit from system_error.h

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210728 91177308-0d34-0410-b5e6-96231b3b80d8
Used mapWindowsError. I missed these in the initial transition.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210729 91177308-0d34-0410-b5e6-96231b3b80d8
Don't import error_condition into the llvm namespace.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210731 91177308-0d34-0410-b5e6-96231b3b80d8
Don't import error_category into the llvm namespace.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210733 91177308-0d34-0410-b5e6-96231b3b80d8
Fix verifier for GlobalAliases to avoid recursing into global initializers.

The verifier follows GlobalAlias operands so that it can detect cycles of
alias definitions. It was doing this in a way that caused it to also recurse
through initializers for the GlobalValue aliasees, and it would fail when
an initializer refers to a global that is a declaration and not a definition.
This patch causes it to stop recursing when it hits a global definition.
<rdar://problem/17277451>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210734 91177308-0d34-0410-b5e6-96231b3b80d8