perf build: Unconditionally set up libunwind feature build flags

A "make feature-dump" build does not specify LIBUNWIND=1 because it is
run with the default configuration to detect system-wide capabilities.
This sets NO_LIBUNWIND := 1, causing Makefile.config to skip setting
LIBUNWIND_LIBS and FEATURE_CHECK_LDFLAGS-libunwind.

Consequently, when Makefile.feature is included and attempts to run
all feature checks (via FEATURE_TESTS := all), the local feature test
test-libunwind.bin compiles without the required architecture-specific
library flags (-lunwind-x86_64) and fails to link on x86_64. This
results in a corrupted cached BUILD_TEST_FEATURE_DUMP showing
feature-libunwind=0 even when the host supports it.

Subsequent test builds (like make_libunwind_O in the build-test suite)
which reuse the feature dump and specify LIBUNWIND=1 will fail to
compile due to a mismatch where CONFIG_LIBUNWIND is set (via remote
architecture checks which are self-contained) but HAVE_LIBUNWIND_SUPPORT
is disabled, causing compiler errors due to missing maps__e_machine
definitions in maps.h.

Fix this by unconditionally setting up the libunwind library lists
and feature check LDFLAGS in Makefile.config so they are always
populated and available to the feature detection engine regardless
of whether LIBUNWIND=1 is opted-in for the current run.

Fixes: 444508cd7c7b4f05 ("perf build: Be more programmatic when setting up libunwind variables")
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0 files changed, 0 insertions, 0 deletions