[PATCH v2 2/3] perf: build: Minor improvement for linking libzstd

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

The zstd library will be automatically linked automatically 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>
---
 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