Make these CHECKs a bit more strict.

The " at the end of the line makes sure we matched the entire directive.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209599 91177308-0d34-0410-b5e6-96231b3b80d8
Emit data or code export directives based on the type.

Currently we look at the Aliasee to decide what type of export
directive to use. It seems better to use the type of the alias
directly. This is similar to how we handle the alias having the
same address but other attributes (linkage, visibility) from the
aliasee.

With this patch it is now possible to do things like

target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-windows-msvc"
@foo = global [6 x i8] c"\B8*\00\00\00\C3", section ".text", align 16
@f = dllexport alias i32 (), [6 x i8]* @foo
!llvm.module.flags = !{!0}
!0 = metadata !{i32 6, metadata !"Linker Options", metadata !1}
!1 = metadata !{metadata !2, metadata !3}
!2 = metadata !{metadata !"/DEFAULTLIB:libcmt.lib"}
!3 = metadata !{metadata !"/DEFAULTLIB:oldnames.lib"}

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209600 91177308-0d34-0410-b5e6-96231b3b80d8