Ubuntu won't make htslib-1.3.1

Start with zfio.c and the bgzip build target shown in the report, then reproduce the failure with the provided configure and make commands on Ubuntu 12.04. Trace the undefined gzgetc_ reference and confirm that a successful build of bgzip completes without the linker error.

Hello
I am trying to install htslib-1.3.1 on Ubuntu 12.04 using ./configure and make but getting the following error message. Also I have verified that zlib1g-dev is installed and up to date on the server.

Any help would be much appreciated.
Matt

gcc -g -O2 -I. -fpic -c -o cram/rANS_static.pico cram/rANS_static.c
gcc -g -O2 -I. -fpic -c -o cram/sam_header.pico cram/sam_header.c
gcc -g -O2 -I. -fpic -c -o cram/string_alloc.pico cram/string_alloc.c
gcc -g -O2 -I. -fpic -c -o cram/thread_pool.pico cram/thread_pool.c
gcc -g -O2 -I. -fpic -c -o cram/vlen.pico cram/vlen.c
gcc -g -O2 -I. -fpic -c -o cram/zfio.pico cram/zfio.c
gcc -shared -Wl,-soname,libhts.so.2 -pthread -o libhts.so kfunc.pico knetfile.pico kstring.pico bgzf.pico errmod.pico faidx.pico hfile.pico hfile_net.pico hts.pico md5.pico probaln.pico realn.pico regidx.pico sam.pico synced_bcf_reader.pico vcf_sweep.pico tbx.pico vcf.pico vcfutils.pico cram/cram_codecs.pico cram/cram_decode.pico cram/cram_encode.pico cram/cram_external.pico cram/cram_index.pico cram/cram_io.pico cram/cram_samtools.pico cram/cram_stats.pico cram/files.pico cram/mFILE.pico cram/open_trace_file.pico cram/pooled_alloc.pico cram/rANS_static.pico cram/sam_header.pico cram/string_alloc.pico cram/thread_pool.pico cram/vlen.pico cram/zfio.pico -lz -lm
ln -sf libhts.so libhts.so.2
gcc -g -O2 -I. -c -o bgzip.o bgzip.c
gcc -pthread -o bgzip bgzip.o libhts.a -lz
libhts.a(zfio.o): In function zfpeek': zfio.c:(.text+0x121): undefined reference togzgetc_'
collect2: error: ld returned 1 exit status
make: *** [bgzip] Error 1