libmodule-build-perl: Use env utility to find perl interpreter

Fixes
ERROR: QA Issue: : /work/x86_64-linux/libmodule-build-perl-native/0.4231-r0/sysroot-destdir/work/x86_64-linux/libmodule-build-perl-native/0.4231-r0/recipe-sysroot-native/usr/bin/config_data maximum shebang size exceeded, the maximum size is 128. [shebang-size]

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>