[PATCH v3 2/3] perf: build: Minor improvement for linking libzstd

[Leo Yan <leo.yan@arm.com>]

The zstd library will be automatically linked by detecting the feature
libzstd.  It is no need to explicitly link it for static builds, so
remove the redundant linkage.

It is contradictory to detect the feature libelf-zstd while the build
configuration NO_LIBZSTD is set.  Report an error for reminding users
not to set NO_LIBZSTD.

Signed-off-by: Leo Yan <leo.yan@arm.com>
Tested-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/perf/Makefile.config | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 0e4f6a860ae2..155cb9d20011 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -171,7 +171,7 @@ ifdef LIBDW_DIR
 endif
 DWARFLIBS := -ldw
 ifeq ($(findstring -static,${LDFLAGS}),-static)
-  DWARFLIBS += -lelf -lz -llzma -lbz2 -lzstd
+  DWARFLIBS += -lelf -lz -llzma -lbz2
 
   LIBDW_VERSION := $(shell $(PKG_CONFIG) --modversion libdw).0.0
   LIBDW_VERSION_1 := $(word 1, $(subst ., ,$(LIBDW_VERSION)))
@@ -566,6 +566,12 @@ ifndef NO_LIBELF
     CFLAGS += -DHAVE_ELF_GETSHDRSTRNDX_SUPPORT
   endif
 
+  ifeq ($(feature-libelf-zstd), 1)
+    ifdef NO_LIBZSTD
+      $(error Error: libzstd is required by libelf, please do not set NO_LIBZSTD)
+    endif
+  endif
+
   ifndef NO_LIBDEBUGINFOD
     $(call feature_check,libdebuginfod)
     ifeq ($(feature-libdebuginfod), 1)
-- 
2.34.1