Make buildsystem respect GNU conventions
* CPPFLAGS is a user variable and should be respected
when compiling .c files. Think of -D_FORTIFY_SOURCE=2.
* Pass ALL_CFLAGS when linking too. This is recommended
for certain edge cases (-flto)
* Use DESTDIR instead of INSTALLROOT for staging dir
Every other build system (Automake, CMake, Meson) uses
DESTDIR. This integrates better into distro and other
build systems that have standard hooks for DESTDIR.
* $(MAKE) -C <dir> is better than cd'ing into a <dir>
* Use Autoconf's ${docdir} and ${htmldir} for installing
the documentation. This makes handling documentation
easier and respects user choice.
Signed-off-by: David Seifert <soap@gentoo.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>