Improve some of the conversion warnings to fire on conversion to bool.

Moves the bool bail-out down a little in SemaChecking - so now
-Wnull-conversion and -Wliteral-conversion can fire when the target type is
bool.

Also improve the wording/details in the -Wliteral-conversion warning to match
the -Wconstant-conversion.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156826 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Sema/knr-def-call.c b/test/Sema/knr-def-call.c
index f41275d..80ad0d8 100644
--- a/test/Sema/knr-def-call.c
+++ b/test/Sema/knr-def-call.c
@@ -36,6 +36,6 @@
 }
 
 void use_proto() {
-  proto(42.1); // expected-warning{{implicit conversion turns literal floating-point number into integer}}
-  (&proto)(42.1); // expected-warning{{implicit conversion turns literal floating-point number into integer}}
+  proto(42.1); // expected-warning{{implicit conversion from 'double' to 'int' changes value from 42.1 to 42}}
+  (&proto)(42.1); // expected-warning{{implicit conversion from 'double' to 'int' changes value from 42.1 to 42}}
 }