Don't count single quote ' as garbage (#1801)

Also copy the "blank space" (space or tab) vs "whitespace" (space,
tab, or newline) convention from `<ctype.h>`

src/CMakeLists.txt

@@ -84,6 +84,7 @@ set(rgbfix_src
     "fix/main.cpp"
     "fix/mbc.cpp"
     "fix/warning.cpp"
+    "util.cpp"
     )
 
 set(rgbgfx_src