Merge branch 'samples: bpf: fix build issues with Clang/LLVM'

Alexander Lobakin says:

====================

Samples, at least XDP ones, can be built only with the compiler used
to build the kernel itself.
However, XDP sample infra introduced in Aug'21 was probably tested
with GCC/Binutils only as it's not really compilable for now with
Clang/LLVM.
These two are trivial fixes addressing this.
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

samples/bpf/Makefile

@@ -215,6 +215,11 @@ TPROGS_LDFLAGS := -L$(SYSROOT)/usr/lib
 endif
 
 TPROGS_LDLIBS			+= $(LIBBPF) -lelf -lz
+TPROGLDLIBS_xdp_monitor		+= -lm
+TPROGLDLIBS_xdp_redirect	+= -lm
+TPROGLDLIBS_xdp_redirect_cpu	+= -lm
+TPROGLDLIBS_xdp_redirect_map	+= -lm
+TPROGLDLIBS_xdp_redirect_map_multi += -lm
 TPROGLDLIBS_tracex4		+= -lrt
 TPROGLDLIBS_trace_output	+= -lrt
 TPROGLDLIBS_map_perf_test	+= -lrt
@@ -345,7 +350,7 @@ $(obj)/hbm_edt_kern.o: $(src)/hbm.h $(src)/hbm_kern.h
 
 # Override includes for xdp_sample_user.o because $(srctree)/usr/include in
 # TPROGS_CFLAGS causes conflicts
-XDP_SAMPLE_CFLAGS += -Wall -O2 -lm \
+XDP_SAMPLE_CFLAGS += -Wall -O2 \
 		     -I$(src)/../../tools/include \
 		     -I$(src)/../../tools/include/uapi \
 		     -I$(LIBBPF_INCLUDE) \

samples/bpf/xdp_sample_user.h

@@ -45,7 +45,9 @@ const char *get_driver_name(int ifindex);
 int get_mac_addr(int ifindex, void *mac_addr);
 
 #pragma GCC diagnostic push
+#ifndef __clang__
 #pragma GCC diagnostic ignored "-Wstringop-truncation"
+#endif
 __attribute__((unused))
 static inline char *safe_strncpy(char *dst, const char *src, size_t size)
 {