devel/android-tools-*: slightly improve standalone build
- Try to derive {ADB,FASTBOOT}_REVISION from git(1)
- Use pkg-config for libcrypto/libpcre/libusb (e.g. if they aren't in base)
- Convert PORTDOCS into FILES (bsd.port.mk vs. bsd.prog.mk)
- Partially convert to new testing framework
- Put -lpthread last as enforced by base r274849 but prevent := assignment from mucking $ escaping in $()
- |make clean| to clean files built by test target
- Move up bsd.prog.mk in order to use ${PROG} and ${OBJS} defined in it