Configure script does not check for lack of pthreads (and/or libzcmq.so does not pull it in)

[jimklimov]

A test for libmagic (OS-packaged without a pkgconfig) failed in fallback to compilation because in fact pthreads were not there:

configure:20103: result: yes
configure:20115: checking for magic_close in -lmagic
configure:20140: gcc -std=gnu99 -o conftest   -I/usr/include/tnt       -DMLM_BUILD_DRAFT_API=1         -O2 -g -pipe -Wal
l -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches   -m64 -
mtune=generic  -Wl,-z,relro  conftest.c -lmagic  -ltntdb   -ltntnet   -lcxxtools   -lcidr   -lmlm -lczmq -lzmq   -lczmq
-lzmq   -lzmq   -lsodium    >&5
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libczmq.so: error: undefined reference to 'pthread_create'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libczmq.so: error: undefined reference to 'pthread_mutex_tryloc
k'
/usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libczmq.so: error: undefined reference to 'pthread_detach'
collect2: error: ld returned 1 exit status
configure:20140: $? = 1
configure: failed program was:
...
configure:20149: result: no
configure:20282: WARNING: Cannot find pkg-config metadata for libmagic 0.0.0 or higher

Although it seems to be linked:

# chroot /var/cache/obs/worker/root_5/ /usr/bin/ldd  /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/libczmq.so
        linux-vdso.so.1 =>  (0x00007ffd533f9000)
        libzmq.so.4 => /lib64/libzmq.so.4 (0x00007f04451cb000)
        libc.so.6 => /lib64/libc.so.6 (0x00007f0444dfe000)
        libsodium.so.13 => /lib64/libsodium.so.13 (0x00007f0444ba6000)
        librt.so.1 => /lib64/librt.so.1 (0x00007f044499e000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f0444782000)
        libstdc++.so.6 => /lib64/libstdc++.so.6 (0x00007f0444479000)
        libm.so.6 => /lib64/libm.so.6 (0x00007f0444177000)
        libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f0443f61000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f04456e6000)