package/c-icap: fix musl build

Commit cb5df2fe wrongly removed the
first patch which is not in version 0.5.6. So add it back and update it
so that it applies cleanly.

Fixes:
 - http://autobuild.buildroot.org/results/ddb57462945c5c2340cc375aa6fe2848d13d7001



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