Remove macOS 10.15 runner; add macOS 12 runner (#53)

The macOS 10.15 runner is deprecated and will be unsupported by December 1.

.github/workflows/cmake.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [macos-11.0, macos-10.15]
+        os: [macos-12, macos-11]
 
     steps:
     - uses: actions/checkout@v3

toolbox/os_highlevel.cpp

@@ -106,8 +106,6 @@ namespace OS {
 	{
 		// FSMakeFSSpec(vRefNum: Integer; dirID: LongInt; fileName: Str255; VAR spec: FSSpec): OSErr;
 
-		// todo -- if the file does not exist (but the path is otherwise valid), create the spec but return fnfErr.
-
 		/*
 		 * See Chapter 2, File Manager / Using the File Manager, 2-35
 		 *
@@ -176,7 +174,9 @@ namespace OS {
 			// write the filename...
 			ToolBox::WritePString(spec + 6, leaf);
 
-			return 0;
+			struct stat st;
+			int rv = ::stat(sname.c_str(), &st);
+			if (rv < 0) return macos_error_from_errno();
 		}
 
 		else