[msan] Rewrite strto* interceptors and add a few more.

Express the strto* interceptors though macros. This removes a lot of
duplicate code and fixes a couple of copypasto bugs (where "res" was declared of
a different type than the actual return type). Also, add a few more interceptors
for strto*_l.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@200316 91177308-0d34-0410-b5e6-96231b3b80d8