[opaque pointer type] Add textual IR support for explicit type parameter to load instruction

Essentially the same as the GEP change in r230786.

A similar migration script can be used to update test cases, though a few more
test case improvements/changes were required this time around: (r229269-r229278)

import fileinput
import sys
import re

pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)")

for line in sys.stdin:
  sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line))

Reviewers: rafael, dexonsmith, grosser

Differential Revision: http://reviews.llvm.org/D7649

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230794 91177308-0d34-0410-b5e6-96231b3b80d8

test/Feature/memorymarkers.ll

@@ -26,7 +26,7 @@ entry:
   ;; Constructor has finished here.
   %inv = call {}* @llvm.invariant.start(i64 8, i8* %y)
   call void @_Z3barRKi(i32* %0) nounwind
-  %2 = load i32* %0, align 8
+  %2 = load i32, i32* %0, align 8
 
   ;; Destructor is run here.
   call void @llvm.invariant.end({}* %inv, i64 8, i8* %y)