build: avoid double definition of zbc_log_drv etc.

[jengelh]

When -fno-common is in use, what compiler writers are trying to make a standard, libzbc fails to build.

$ make V=1 Making all in . make[1]: Entering directory '/home/jengelh/obs/zu/hardware/libzbc/libzbc' /bin/sh ./libtool --tag=CC --mode=link gcc -fPIC -fno-common -O2 -g -pthread -Wl,--version-script,./exports -release '5.8.5' -o libzbc.la -rpath /usr/lib lib/libzbc_la-zbc.lo lib/libzbc_la-zbc_block.lo lib/libzbc_la-zbc_sg.lo lib/libzbc_la-zbc_scsi.lo lib/libzbc_la-zbc_ata.lo lib/libzbc_la-zbc_fake.lo libtool: link: gcc -shared -fPIC -DPIC lib/.libs/libzbc_la-zbc.o lib/.libs/libzbc_la-zbc_block.o lib/.libs/libzbc_la-zbc_sg.o lib/.libs/libzbc_la-zbc_scsi.o lib/.libs/libzbc_la-zbc_ata.o lib/.libs/libzbc_la-zbc_fake.o -O2 -g -pthread -Wl,--version-script -Wl,./exports -pthread -Wl,-soname -Wl,libzbc-5.8.5.so -o .libs/libzbc-5.8.5.so /usr/lib64/gcc/x86_64-suse-linux/9/../../../../x86_64-suse-linux/bin/ld: lib/.libs/libzbc_la-zbc_block.o:/home/jengelh/obs/zu/hardware/libzbc/libzbc/lib/zbc.h:269: multiple definition of zbc_log_level'; lib/.libs/libzbc_la-zbc.o:/home/jengelh/obs/zu/hardware/libzbc/libzbc/lib/zbc.h:269: first defined here /usr/lib64/gcc/x86_64-suse-linux/9/../../../../x86_64-suse-linux/bin/ld: lib/.libs/libzbc_la-zbc_block.o:/home/jengelh/obs/zu/hardware/libzbc/libzbc/lib/zbc.h:195: multiple definition ofzbc_fake_drv'; lib/.libs/libzbc_la-zbc.o:/home/jengelh/obs/zu/hardware/libzbc/libzbc/lib/zbc.h:195: first defined here

References: https://bugzilla.suse.com/show_bug.cgi?id=1160244

[damien-lemoal]

Applied. Thanks !