-Wsign-compare shouldn't warn when the signed operand is a conditional operator
whose operands are non-negative integer constant expressions.  This comes up
in LLVM in a few places.

llvm-svn: 92525
diff --git a/clang/test/Sema/compare.c b/clang/test/Sema/compare.c
index 75a3cf1f6..bacd47e 100644
--- a/clang/test/Sema/compare.c
+++ b/clang/test/Sema/compare.c
@@ -194,6 +194,9 @@
          ((short) a < (unsigned short) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
          ((signed char) a < (unsigned char) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
 
+         // We should be able to avoid warning about this.
+         (b != (a < 4 ? 1 : 2)) +
+
          10
     ;
 }