[PATCH] Add minnum / maxnum intrinsics

[hfinkel at anl.gov]

LGTM, thanks!

================
Comment at: lib/Transforms/InstCombine/InstCombineCalls.cpp:551
@@ +550,3 @@
+    if (isa<UndefValue>(Arg1))
+      return ReplaceInstUsesWith(CI, Arg0);
+
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I believe this to be correct, we cannot return undef because we're prohibited from making the output NaN (even if the input is NaN so long as both inputs are not NaN). But please add a comment explaining this.

http://reviews.llvm.org/D5716