e2fsprogs: disable parallel build for host installation

e2fsprogs: disable parallel build for host installation

It seems that host-e2fsprogs has an issue with parallel build since
version 1.44.2:

symlinks.o: file not recognized: File truncated

/home/buildroot/build/instance-0/output/host/lib/libss.so.2: file or directory does not exist

Fixes:

 - http://autobuild.buildroot.org/results/6b424ba788ccd738c2afcd940075991581e860b6
 - http://autobuild.buildroot.org/results/1d816f9be6bad6e10d273dc2d0acb200233d8d4d

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>