libbpf: fix up global symbol counting logic

Add the same negative ABS filter that we use in VERSIONED_SYM_COUNT to
filter out ABS symbols like LIBBPF_0.8.0.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220518185915.3529475-2-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/lib/bpf/Makefile

@@ -127,7 +127,7 @@ TAGS_PROG := $(if $(shell which etags 2>/dev/null),etags,ctags)
 GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \
 			   cut -d "@" -f1 | sed 's/_v[0-9]_[0-9]_[0-9].*//' | \
 			   sed 's/\[.*\]//' | \
-			   awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
+			   awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print $$NF}' | \
 			   sort -u | wc -l)
 VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
 			      sed 's/\[.*\]//' | \