Add static cast to unsigned char whenever a character classification function is called with a signed char argument, in order to avoid assertions in Windows Debug configuration.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175006 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/IR/InlineAsm.cpp b/lib/IR/InlineAsm.cpp
index 10d281b..9f2a9fe 100644
--- a/lib/IR/InlineAsm.cpp
+++ b/lib/IR/InlineAsm.cpp
@@ -151,10 +151,10 @@
       if (ConstraintEnd == E) return true;  // "{foo"
       pCodes->push_back(std::string(I, ConstraintEnd+1));
       I = ConstraintEnd+1;
-    } else if (isdigit(*I)) {     // Matching Constraint
+    } else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint
       // Maximal munch numbers.
       StringRef::iterator NumStart = I;
-      while (I != E && isdigit(*I))
+      while (I != E && isdigit(static_cast<unsigned char>(*I)))
         ++I;
       pCodes->push_back(std::string(NumStart, I));
       unsigned N = atoi(pCodes->back().c_str());