stage2: fix C ABI for bool

This fixes a miscompilation compiling debug zig with release stage3 zig.

src/codegen/llvm.zig

@@ -10277,6 +10277,7 @@ fn ccAbiPromoteInt(
         else => {},
     }
     const int_info = switch (ty.zigTypeTag()) {
+        .Bool => Type.@"u1".intInfo(target),
         .Int, .Enum, .ErrorSet => ty.intInfo(target),
         else => return null,
     };