e2fsprogs: avoid picking up incompatible libcom_err.so

Commit 2728512e ("e2fsprogs: List all libraries explicitly") forced the
e2fsprogs build system to link libcom_err.so in various places.

Unfortunately, the krb5 package also ships a libcom_err.so with a totally
different ABI and puts it into the global staging directory which causes
e2fsprogs to pick up this wrong library, leading to the following failure:

    	LD blkid
    ../lib/libext2fs.so: undefined reference to `_et_list'
    collect2: error: ld returned 1 exit status
    Makefile:504: recipe for target 'blkid' failed

Change the SYSLIBS specification to explicitely link libcom_err.so.0.0
which in order to work around the problem.

In the long run, the libcom_err clash between e2fsprogs and krb5 needs to
be solved properly.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>