Followed the instructions in the php manual for installing
yaz-1.6 from source. Then, installing php,

Configure line was:

./configure --disable-inline --disable-debug \
--with-apxs=/usr/sbin/apxs --with-msql=/usr/local/Hughes \
--with-pgsql=/usr/include/pgsql --enable-ftp --with-zlib \
--with-xml --with-mysql --with-mcrypt=/usr/local/lib \
--with-mhash=/usr/local/lib --with-mcal=/usr/src/libmcal \
--with-imap=/usr/include/imap --with-swf=/usr/local/lib \
--with-interbase=/usr/interbase --with-ldap=/usr \
--enable-wddx --enable-sysvsem --enable-sysvshm \
--with-jpeg-dir=/usr/src/jpeg-6b \
--with-xpm-dir=/usr/X11R6/ --with-t1lib=/usr/local \
--with-gd=/usr/local --enable-bcmath \
--with-pfpro=/usr/local --with-curl=/usr/local \
--with-pspell=/usr/local --with-tiff-dir=/usr/lib \
--with-pdflib=/usr/local --with-yaz=/usr/bin

and shows:
checking for YAZ support... yes
...
creating ext/yaz/Makefile
...

Executing 'make' ends with:

/usr/bin/ld: .libs/libphp4.so: undefined versioned symbol
 name log_file@@GLIBC_2.1
/usr/bin/ld: failed to set dynamic section sizes: Bad value
collect2: ld returned 1 exit status
make[1]: *** [libphp4.la] Error 1
make[1]: Leaving directory `/usr/src/phpdev'
make: *** [all-recursive] Error 1

Removing the yaz flag, php compiles and installs
without any problems.