cmake: get cpp-httplib libraries from pkgconf

[dankamongmen]

openvino-audacity requires libcpp-httlib, but doesn't look it up in CMake. REQUIRE it, so that we fail at configuration time if it's not available, and properly pass -l options when it is.

without this, we fail with:

[ 98%] Building CXX object modules/mod-openvino/CMakeFiles/mod-openvino.dir/OVWhisperTranscription.cpp.o
[ 98%] Linking CXX shared module ../../RelWithDebInfo/lib/audacity/modules/mod-openvino.so
/usr/bin/ld: cannot find -lhttplib: No such file or directory
collect2: error: ld returned 1 exit status

[RyanMetcalfeInt8]

Hi @dankamongmen -- not sure how I missed this PR...

Hmm, I'm not really sure where the httplib dependency is coming from... which Linux distro are you building on? I haven't observed this error in my Ubuntu 22/24 or Windows builds.

[dankamongmen]

debian unstable

[dankamongmen]

i do not see httplib linked into the final mod-openvino.so. presumably it's coming from some .pc file dependency. let me look around (and verify that the newest code still needs this).

[dankamongmen]

ugh let's see if i can get this building at all again

[RyanMetcalfeInt8]

Not sure if this helps (i.e. how close Debian 12 is to unstable), but someone just contributed a debian 12 build guide here: https://github.com/intel/openvino-plugins-ai-audacity/blob/main/doc/build_doc/linux/debian12_installation.md

[dankamongmen]

oh, i was able to get it working just fine back when i was working with it, two months ago. if you don't think this is applicable, we can close it up.