Comment 4 for bug 612580

Worth checking with one line added to "unpatch" target: "rm -f patch-stamp" like it is done in eglibc.

All configure-*-stamps depend on 'patch-stamp' so it should be safe with this.

I tested my patch with native and cross builds of binutils. During build first step is "clean" which depends on "unpatch" so when you fix something in 'binary' target then rebuild does unpatching anyway.