BSD make only evaluates $< for implicit rules, so building from the
repository won't work unless GNU make is installed and used, or we
replace affected uses like this.
When missing gperf, the redirection generates an empty file, which must
be manually removed after gperf has been installed. This is difficult
to diagnose, as the produced build error is cryptic.
Use --output-file of gperf instead to avoid creating an empty file if
gperf is missing. This still requires the user to re-run ./configure
after installing gperf, though.
The fix for gperf in 0ae19f0ced added the generated header to
EXTRA_DIST but that's already added to the distribution because it is
contained in *_SOURCES, what was not added, though, was the .h.in file.
Also fixes the reference to the header file in the .c rule here and for
stroke in out-of-tree builds.
Fixes: 0ae19f0ced ("configure: Fix gperf length parameter determination")
gperf is not actually a build dependency as the generated files are
shipped in the tarball. So the type depends on the gperf version on
the host that ran gperf and created the tarball, which might not be
the same as that on the actual build host, and gperf might not even
be installed there, leaving the type undetermined.
Fixes: e0e4322973 ("configure: Detect type of length parameter for gperf generated function")
INCLUDES are now deprecated and throw warnings when using automake 1.13.
We now also differentiate AM_CPPFLAGS and AM_CFLAGS, where includes and
defines are passed to AM_CPPFLAGS only.
Tobias Brunner