* build-package.sh: allow for arrays in TERMUX_PKG_{SRCURL,SHA256}
Packages that require several source archives can then set these parameters to
arrays instead of downloading them "manually" in termux_step_post_extract.
Downloaded files are extracted into subfolders in TERMUX_PKG_SRCDIR.
Tested for backward compatibility in a couple of packages and the combinations
tar + tar, zip + tar, tar + zip, zip + zip.
* perl: download perl-cross through TERMUX_PKG_SRCURL
* perl: remove $PREFIX/{lib/libperl.so,include/perl} before build
Otherwise building perl twice doesn't give the same results, symlinks are
messed up.
Also remove old remnant from when there was a Kid.pm.patch.
* bash: fix tiny typo
* ecj: remove hardcoded SHA256 and pkg version
* elfutils: download argp-standalone through TERMUX_PKG_SRCURL
* ldc: download all src archives through TERMUX_PKG_SRCURL
* libgc: download libatomic_ops through TERMUX_PKG_SRCURL
* libllvm: download all src archives through TERMUX_PKG_SRCURL
* linux-man-pages: download src archives through TERMUX_PKG_SRCURL
* ncurses: download all src archives through TERMUX_PKG_SRCURL
* pngquant: download lib sources through TERMUX_PKG_SRCURL
Use .zip for lib since the downloaded archives are otherwise both named
$TERMUX_PKG_VERSION.tar.gz and replace each other. This causes caching to
not work.
