remove patch from busybox built-ins

busybox patch is a prototype, it works only when the patch to be applied requires zero fuzz. therefore it is broken as this means as soon as you update the version of package to be applied to it will cause an error, or if you have multiple patches that touch the same file. alpine developers are quite aware of the brokenness, that's why the real patch program is in deps for abuild.

removing patch from busybox has the following advantages:

• shaving off 10-20KB from minimal docker image
• people maintaing projects that require a working patch program don't need to add a configure check "checking whether patch works ... no, broken alpine patch which doesn't support fuzz detected"

note that alpine is the only distro i'm aware of that has the broken busybox patch in its base install.

additionally patch is a developer's tool with zero relation to POSIX tools mandated in a base install (i.e. it's not a coreutils-league program). having it built into busybox is roughly equivalent to adding and enabling tcc (tiny C Compiler) to busybox. the result will be to have a semi-working developer tool nobody serious will use in the base install.