perf build: Fix library not found error when using CSLIBS

-L only specifies the search path for libraries directly provided in the
link line with -l. Because -lopencsd isn't specified, it's only linked
because it's a dependency of -lopencsd_c_api. Dependencies like this are
resolved using the default system search paths or -rpath-link=... rather
than -L. This means that compilation only works if OpenCSD is installed
to the system rather than provided with the CSLIBS (-L) option.

This could be fixed by adding -Wl,-rpath-link=$(CSLIBS) but that is less
conventional than just adding -lopencsd to the link line so that it uses
-L. -lopencsd seems to have been removed in commit ed17b1914978eddb
("perf tools: Drop requirement for libstdc++.so for libopencsd check")
because it was thought that there was a chance compilation would work
even if it didn't exist, but I think that only applies to libstdc++ so
there is no harm to add it back. libopencsd.so and libopencsd_c_api.so
would always exist together.

Testing
=======

The following scenarios now all work:

 * Cross build with OpenCSD installed
 * Cross build using CSLIBS=...
 * Native build with OpenCSD installed
 * Native build using CSLIBS=...
 * Static cross build with OpenCSD installed
 * Static cross build with CSLIBS=...

Committer testing:

  ⬢[acme@toolbox perf-tools]$ alias m
  alias m='make -k BUILD_BPF_SKEL=1 CORESIGHT=1 O=/tmp/build/perf-tools -C tools/perf install-bin && git status && perf test python ;  perf record -o /dev/null sleep 0.01 ; perf stat --null sleep 0.01'
  ⬢[acme@toolbox perf-tools]$ ldd ~/bin/perf | grep csd
  	libopencsd_c_api.so.1 => /lib64/libopencsd_c_api.so.1 (0x00007fd49c44e000)
  	libopencsd.so.1 => /lib64/libopencsd.so.1 (0x00007fd49bd56000)
  ⬢[acme@toolbox perf-tools]$ cat /etc/redhat-release
  Fedora release 36 (Thirty Six)
  ⬢[acme@toolbox perf-tools]$

Fixes: ed17b1914978eddb ("perf tools: Drop requirement for libstdc++.so for libopencsd check")
Reported-by: Radhey Shyam Pandey <[email protected]>
Signed-off-by: James Clark <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Tested-by: Radhey Shyam Pandey <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Uwe Kleine-König <[email protected]>
Cc: [email protected]
Closes: https://lore.kernel.org/linux-arm-kernel/[email protected]/
Link: https://lore.kernel.org/all/[email protected]/
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions