ffi M1.0 (2/3, xfail): '=>' body inside '#objc_class' member

parseForeignClassDecl ([src/parser.zig:1262]) accepts ';'
(declaration) or '{ ... }' (block body) but not '=>' for member
methods. The arrow form, which parseFnDecl ([src/parser.zig:1647])
already handles for top-level/struct decls (M1.0 1/3), surfaces
'expected ;' at the arrow today.

Snapshot pins that error so the next commit (the parser
extension) shows up as a single diagnostic→runtime-output diff
in 140-expression-bodied-objc-method.{txt,exit}.

tests/expected/140-expression-bodied-objc-method.exit

@@ -0,0 +1 @@
+1

tests/expected/140-expression-bodied-objc-method.txt

@@ -0,0 +1 @@
+/Users/agra/projects/sx/examples/140-expression-bodied-objc-method.sx:15:35: error: expected ';'