builtins: whitespace

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@214044 91177308-0d34-0410-b5e6-96231b3b80d8
builtins: move macro definitions into assembly.h

The macro definitions are shared across multiple files.  Define them once in the
assembly.h header rather than redefining it in each file.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@214045 91177308-0d34-0410-b5e6-96231b3b80d8