lib-*.m4 not up to date with gettext-0.21
Our bootstrap is supposed to be up-to-date with gettext-0.21 (and patches to go beyond on review/on works). We've missed m4/lib-*.m4 files when updating to gettext-0.21 level.
We were supposed to be on gettext-0.21 level in 2.6.3 already, and there has been no problems reported because of the older lib-*.m4 files, so supposedly this is not critical - not something that still needs to be fixed in upcoming 3.0.0-beta1 and 2.6.4 releases.
Pushed to master & S3_1
Pushed also to S3_0, leaving only S2_6
For S2_6 the current patch causes #41819 - host-cpu-c-abi.m4 should also be added when updating lib-ld.m4.
Added S2_6 version that adds host-cpu-c-abi.m4
#41843 started when this was pushed.
S2_6 version that does not introduce #41843 to the branch.