hfsprogs: Fix build failures with external toolchains
Several problems were found with building against an external toolchain:
* TARGET_CPPFLAGS was missing which would prevent finding the headers
* TARGET_LDFLAGS also was not passed correctly
* when building against glibc, since we use strlcpy() we need to link
against libbsd
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>