* gnu/packages/engineering.scm (libmodbus): Update to 3.1.11. Add a missing
newline after the package definition.
[source]: Add a patch which disables a test that requires networking.
* gnu/packages/patches/libmodbus-disable-networking-test.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
Change-Id: I657c0aac3435ec20da6e15d31484effdb7c2dc0b