configure.ac: find libpsl with pkg-config

[ffontaine]

Find libpsl with pkg-config to avoid the following static build failure:

configure:28830: /home/autobuild/autobuild/instance-6/output-1/host/bin/aarch64_be-buildroot-linux-musl-gcc -o conftest -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O3 -g0 -static -Werror-implicit-function-declaration -Wno-system-headers -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -I/home/autobuild/autobuild/instance-6/output-1/host/aarch64_be-buildroot-linux-musl/sysroot/usr/include  -static -L/home/autobuild/autobuild/instance-6/output-1/host/bin/../aarch64_be-buildroot-linux-musl/sysroot/usr/lib  -L/home/autobuild/autobuild/instance-6/output-1/host/aarch64_be-buildroot-linux-musl/sysroot/usr/lib conftest.c -lpsl  -lmbedtls -lmbedx509 -lmbedcrypto -lz  -latomic >&5
/home/autobuild/autobuild/instance-6/output-1/host/lib/gcc/aarch64_be-buildroot-linux-musl/11.4.0/../../../../aarch64_be-buildroot-linux-musl/bin/ld: /home/autobuild/autobuild/instance-6/output-1/host/bin/../aarch64_be-buildroot-linux-musl/sysroot/usr/lib/libpsl.a(psl.c.o): in function `is_public_suffix':
psl.c:(.text+0x2a8): undefined reference to `idn2_lookup_u8'

[...]

checking for library containing psl_builtin... no
configure: error: libpsl was not found

Fixes:

• http://autobuild.buildroot.org/results/1fb15e1a99472c403d0d3b1a688902f32e78d002

[dfandrich]

The test failures look relevant, probably related to removing AM_CONDITIONAL.

[ffontaine]

Thanks for your review, PR was updated

[jay]

I assume you mean --with-libpsl and why would we not want to allow it without pkg-config?

[ffontaine]

I'll rename --libpsl to --with-libpsl.
If --with-libpsl is provided, but pkg-config file is not found, an error is raised as already done by libcurl when handling librtmp, nghttp2, ngtcp2, nghttp3 and quiche. However, it seems that curl is not very consistent as other options don't raise such kind of failure.

[bagder]

It is not consistent as to whether that is an error or not, correct. Like in this case, curl has built fine with libpsl for decades without pkg-config, so maybe it could be worth keeping that ability just to make existing setups keep working?

[ffontaine]

PR was updated

[bagder]

Thanks!