Remove external_libraries headers for icu and tinygettext, as they
neither add any workarounds needed and as quite a few other libraries
don't have such a header either. As for the warnings suppressed, this is
no longer needed as they were fixed and with vs2019 added support for
-isystem or equivalent would make this useless eitherway.
Further make include-what-you-use happy with files in source/118n and
fix what needs to be fixed after.
Ref: #8086
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Ralph Sennhauser
863b0b90b7