devel/fb-adb: unbreak build on DragonFly

configuring in stub-x86 (/wrkdirs/devel/fb-adb/.build/stub-x86)

configure: running /bin/sh /wrkdirs/devel/fb-adb/fb-adb-1.4.4-109-g930ba5f/stub-x86/configure --disable-option-checking '--prefix=/usr/local' '--mandir=/usr/local/man' '--disable-checking' '--disable-debuggable-stubs' '--with-android-ndk=system' '--build=x86_64-portbld-dragonfly4.3' 'build_alias=x86_64-portbld-dragonfly4.3' 'CC=cc' 'CFLAGS=-O2 -pipe' 'LDFLAGS=' 'LIBS=' 'CPPFLAGS=' 'CPP=cpp' --cache-file=/dev/null --srcdir=/wrkdirs/devel/fb-adb/fb-adb-1.4.4-109-g930ba5f/stub-x86
checking build system type... x86_64-portbld-dragonfly4.3
checking host system type... i686-pc-linux-android
Using system Android cross-compilers
[...]
configure: error: could not find Android cross-compiler for i686-pc-linux-android