refactor the MemoryBuiltin analysis:

- provide more extensive set of functions to detect library allocation functions (e.g., malloc, calloc, strdup, etc)
 - provide an API to compute the size and offset of an object pointed by

Move a few clients (GVN, AA, instcombine, ...) to the new API.
This implementation is a lot more aggressive than each of the custom implementations being replaced.

Patch reviewed by Nick Lewycky and Chandler Carruth, thanks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158919 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/objsize.ll

@@ -42,7 +42,7 @@ define i32 @f() nounwind {
 
 define i1 @baz() nounwind {
 ; CHECK: @baz
-; CHECK-NEXT: ret i1 true
+; CHECK-NEXT: objectsize
   %1 = tail call i32 @llvm.objectsize.i32(i8* getelementptr inbounds ([0 x i8]* @window, i32 0, i32 0), i1 false)
   %2 = icmp eq i32 %1, -1
   ret i1 %2