Store defined macros in MCContext.

So that macros defined in inline assembly blocks are available to the
whole file.

This provides a consistent behavior with other assembly directives,
since equations for example are already preserved between inline
assembly blocks.

PR: 36110

Patch by Roger!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325139 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed