Simplest change to change from pcre to pcre2

[paulrho]

[gregoa]

Alright, I added this PR as a patch to the Debian package, and unfortunately the build fails at the linker stage:

gcc -I/usr/include/x86_64-linux-gnu -I/usr/include/libxml2 -I/usr/include/json-c  -I/usr/include/x86_64-linux-gnu -I/usr/include/nss -I/usr/include/nspr -g -O2 -ffile-prefix-map=/build/bti-034=. -fstack-protector-strong -Wformat -Werror=format-security  -Wl,-z,relro -Wl,-z,now -o bti bti-config.o bti-bti.o -lcurl -lxml2 -ljson-c  -loauth -ldl 
/usr/bin/ld: bti-bti.o: in function `find_urls':
/tmp/buildd/bti-034/bti.c:1298: undefined reference to `pcre2_compile_8'
/usr/bin/ld: /tmp/buildd/bti-034/bti.c:1310: undefined reference to `pcre2_match_data_create_from_pattern_8'
/usr/bin/ld: /tmp/buildd/bti-034/bti.c:1312: undefined reference to `pcre2_match_8'
/usr/bin/ld: /tmp/buildd/bti-034/bti.c:1322: undefined reference to `pcre2_get_ovector_pointer_8'
/usr/bin/ld: /tmp/buildd/bti-034/bti.c:1339: undefined reference to `pcre2_code_free_8'
collect2: error: ld returned 1 exit status

If I manually add -lpcre2-8 at the end of the gcc call, it works.

Looks like there's some more autoconf/automake magic needed to get the needed flags in the needed places.

[paulrho]

Okay, try again (pull request is automatically updated with this correction correction). I'd modified the Makefile, but not the Makefile.am - now fixed. I've checked that it builds on a fresh Fedora machine.

[gregoa]

Thanks! This looks good indeed.
I'm able to build the package, and I can even send a tweet with it:
https://twitter.com/gregoa_/status/1462895918596820995
:)