* Improve pkg-config support
1. Add required libraries (zlib, lz4, zstd, openssl, sasl2) to the
pkg-config `Requires` field instead of to `Libs` if they were
discovered via pkg-config. This allows pkg-config (and other tools
built on top of the pkg-config metadata) to see librdkafka's full
dependency graph.
2. Prefix full paths to librdkafka.a with the pkg-config variable
${pc_sysrootdir}. pkg-config automatically applies this prefix to
paths passed to -I and -L, but nowhere else. This means that the
previous link line in the -static.pc files is inconsistent, and
would expand to
-L${pc_sysrootdir}${libdir} ${libdir}/librdkafka.a
3. #include <stddef.h> when checking for sasl so that detection via
pkg-config works. This is needed as sasl.h references some types
that are defined in stddef.h.
* fix sasl includes check
* enable-static: only export pkgconfig deps when no .a is found
This prevents the shared libs to be re-generated on each 'make',
including 'make install', even if there were no changes, which in the case
of 'sudo make install' would create shared libs as the root user.
Prevents errors like
Checking librdkafka integrity
librdkafka.1.dylib OK
librdkafka.a OK
Symbol visibility OK
uname: illegal option -- o
usage: uname [-amnprsv]
Eric Seidel
Magnus Edenhill
David Trihy
twaters
Bob Halley
Scott Halstead
Thomas D
Eugenio Pérez
Kodekarl
Rainer Gerhards