[PATCH v1 10/14] perf build: Remove redundant libbpf feature check for static builds

[Ian Rogers <irogers@google.com>]

By default, the perf tool compiles and statically links against its own
internal copy of libbpf (tools/lib/bpf/libbpf.a), setting LIBBPF_STATIC=1.

Despite this static linkage, Makefile.config unconditionally executed
$(call feature_check,libbpf), which forced a synchronous sub-make fork
during AST parsing to detect dynamic system libbpf libraries.

As noted in the internal Makefile comments, this check was executed purely
so that running `make VF=1` would display the detection status of system
libbpf. During standard builds without LIBBPF_DYNAMIC=1, the detection
result was entirely ignored.

Wrap the libbpf feature check inside LIBBPF_DYNAMIC=1 so Make avoids the
redundant sub-make fork overhead during standard static builds.

Assisted-by: Gemini:gemini-3.1-pro-preview
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/Makefile.config | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index bc1111c88226..fbe7fa83b0bb 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -587,10 +587,8 @@ ifndef NO_LIBELF
 
   ifndef NO_LIBBPF
     ifeq ($(feature-bpf), 1)
-      # detecting libbpf without LIBBPF_DYNAMIC, so make VF=1 shows libbpf detection status
-      $(call feature_check,libbpf)
-
       ifdef LIBBPF_DYNAMIC
+        $(call feature_check,libbpf)
         ifeq ($(feature-libbpf), 1)
           EXTLIBS += -lbpf
           CFLAGS += -DHAVE_LIBBPF_SUPPORT
-- 
2.54.0.563.g4f69b47b94-goog