C++: relax ambiguously-signed-bit-field by allowing GLib's gboolean

The gboolean type of GLib (a widely used C library) is a typedef to int.
It is meant to represent a simple true/false value.

Resolves #7491

Author: MrAnno

cpp/ql/src/Likely Bugs/AmbiguouslySignedBitField.ql

@@ -26,6 +26,8 @@ where
   // At least for C programs on Windows, BOOL is a common typedef for a type
   // representing BoolType.
   not bf.getType().hasName("BOOL") and
+  // GLib's gboolean is a typedef for a type representing BoolType.
+  not bf.getType().hasName("gboolean") and
   // If this is true, then there cannot be unsigned sign extension or overflow.
   not bf.getDeclaredNumBits() = bf.getType().getSize() * 8 and
   not bf.isAnonymous() and