[v6.x backport] src: do not include x.h if x-inl.h is included
Refs: #16518 Refs: #16548
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines
Affected core subsystem(s)
src, doc