weird "undefined reference" errors in config.log when building rsync from source

[devZer0]

does somebody have a clue why these errors appear in config.log during configure run - as all those symbols do exist in .so shared lib or .a static lib?

for me it looks, configure/autoconf is doing wrong, as it missing to add correct -l LIB params to ggc on test cases

these errros go away when adding these manually before configure run

LIBS="-llz4 -lz -lzstd -lxxhash" ./configure

configure.sh:8007: checking for library containing XXH64_createState
configure.sh:8037: gcc -o conftest -I./zlib -g -O2 -DHAVE_CONFIG_H -Wall -W   conftest.c -lcrypto  >&5
/usr/bin/ld: /tmp/ccIgxkS9.o: in function `main':
/tmp/rsync-3.4.1/conftest.c:83:(.text.startup+0x7): undefined reference to `XXH64_createState'
collect2: error: ld returned 1 exit status

configure.sh:8094: checking for library containing ZSTD_minCLevel
configure.sh:8124: gcc -o conftest -I./zlib -g -O2 -DHAVE_CONFIG_H -Wall -W   conftest.c -lxxhash -lcrypto  >&5
/usr/bin/ld: /tmp/ccrCQcuE.o: in function `main':
/tmp/rsync-3.4.1/conftest.c:84:(.text.startup+0x7): undefined reference to `ZSTD_minCLevel'
collect2: error: ld returned 1 exit status

configure.sh:8181: checking for library containing LZ4_compress_default
configure.sh:8211: gcc -o conftest -I./zlib -g -O2 -DHAVE_CONFIG_H -Wall -W   conftest.c -lzstd -lxxhash -lcrypto  >&5
/usr/bin/ld: /tmp/ccv8OS72.o: in function `main':
/tmp/rsync-3.4.1/conftest.c:85:(.text.startup+0x7): undefined reference to `LZ4_compress_default'
collect2: error: ld returned 1 exit status

# nm -D /usr/lib/x86_64-linux-gnu/libxxhash.so|grep XXH64_createState
0000000000004310 T XXH64_createState

# nm -A /usr/lib/x86_64-linux-gnu/libxxhash.a | grep XXH64_createState
/usr/lib/x86_64-linux-gnu/libxxhash.a:xxhash.o:0000000000002050 T XXH64_createState

# nm -D /usr/lib/x86_64-linux-gnu/libzstd.so | grep ZSTD_minCLevel
0000000000030470 T ZSTD_minCLevel

# nm -A /usr/lib/x86_64-linux-gnu/libzstd.a |grep ZSTD_minCLevel
/usr/lib/x86_64-linux-gnu/libzstd.a:zstd_compress.o:000000000000f1d0 T ZSTD_minCLevel

# nm -D /usr/lib/x86_64-linux-gnu/liblz4.so | grep LZ4_compress_default
00000000000073d0 T LZ4_compress_default

# nm -A /usr/lib/x86_64-linux-gnu/liblz4.a |grep LZ4_compress_default
/usr/lib/x86_64-linux-gnu/liblz4.a:lz4.c.o:0000000000003ed0 T LZ4_compress_default

# ldd rsync
	linux-vdso.so.1 (0x00007f4653209000)
	libacl.so.1 => /lib/x86_64-linux-gnu/libacl.so.1 (0x00007f465314f000)
	libpopt.so.0 => /lib/x86_64-linux-gnu/libpopt.so.0 (0x00007f4653140000)
	liblz4.so.1 => /lib/x86_64-linux-gnu/liblz4.so.1 (0x00007f4653119000)
	libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x00007f465304f000)
	libxxhash.so.0 => /lib/x86_64-linux-gnu/libxxhash.so.0 (0x00007f465303c000)
	libcrypto.so.3 => /lib/x86_64-linux-gnu/libcrypto.so.3 (0x00007f4652a00000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f465280b000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f46527eb000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f465320b000)