Add bitnot test for testsuite.

tests/bitnot.qc

@@ -0,0 +1,14 @@
+void main() {
+    float a; a = 1;
+    float b; b = 1;
+    float c; c = 1;
+    float d; d = 1;
+
+    a &~= 1; // 0
+    b &= ~1; // 0
+    c &= ~d; // 0
+
+    print("a: ", ftos(a), "\nb: ",
+                 ftos(b), "\nc: ",
+                 ftos(c), "\n");
+}

tests/bitnot.tmpl

@@ -0,0 +1,9 @@
+# used to test the builtins
+I: bitnot.qc
+D: test bitwise not operators
+T: -execute
+C: -std=gmqcc
+E: $null
+M: a: 0
+M: b: 0
+M: c: 0