tools/build: Add a feature test for libopenssl

It's used by bpftool and the kernel build. Let's add a feature test so
that perf can decide what to do based on the availability.

Signed-off-by: Namhyung Kim <[e-mail]>

tools/build/Makefile.feature

···
         libzstd				\
         disassembler-four-args		\
         disassembler-init-styled	\
-        file-handle
+        file-handle			\
+        libopenssl
 
 # FEATURE_TESTS_BASIC + FEATURE_TESTS_EXTRA is the complete list
 # of all feature tests
···
          lzma                   \
          bpf			\
          libaio			\
-         libzstd
+         libzstd		\
+         libopenssl
 
 #
 # Declare group members of a feature to display the logical OR of the detection

tools/build/feature/Makefile

···
          test-libopencsd.bin			\
          test-clang.bin				\
          test-llvm.bin				\
-         test-llvm-perf.bin   \
+         test-llvm-perf.bin   			\
          test-libaio.bin			\
          test-libzstd.bin			\
          test-clang-bpf-co-re.bin		\
          test-file-handle.bin			\
-         test-libpfm4.bin
+         test-libpfm4.bin			\
+         test-libopenssl.bin
 
 FILES := $(addprefix $(OUTPUT),$(FILES))
 
···
 
 $(OUTPUT)test-libpfm4.bin:
 	$(BUILD) -lpfm
+
+$(OUTPUT)test-libopenssl.bin:
+	$(BUILD) -lssl
 
 $(OUTPUT)test-bpftool-skeletons.bin:
 	$(SYSTEM_BPFTOOL) version | grep '^features:.*skeletons' \

tools/build/feature/test-all.c

···
 # include "test-libtraceevent.c"
 #undef main
 
+#define main main_test_libopenssl
+# include "test-libopenssl.c"
+#undef main
+
 int main(int argc, char *argv[])
 {
 	main_test_libpython();
···
 	main_test_reallocarray();
 	main_test_libzstd();
 	main_test_libtraceevent();
+	main_test_libopenssl();
 
 	return 0;
 }

tools/build/feature/test-libopenssl.c

···
+#include <openssl/ssl.h>
+#include <openssl/opensslv.h>
+
+int main(void)
+{
+	return SSL_library_init();
+}