[WIP] Explicitly install gettext for macos CI

[powerboat9]

This might fix the macos CI

[philberty]

nice try looks like the error is:

checking for -single_module linker flag... clang++ -std=gnu++14  -I../../libcpp -I. -I../../libcpp/../include -I/usr/local/include -I../../libcpp/include -I/usr/local/include -g -O2     -W -Wall -Wno-narrowing -Wwrite-strings -Wmissing-format-attribute -pedantic -Wno-long-long  -fno-exceptions -fno-rtti -I../../libcpp -I. -I../../libcpp/../include -I/usr/local/include -I../../libcpp/include -I/usr/local/include   -c -o charset.o -MT charset.o -MMD -MP -MF .deps/charset.Tpo ../../libcpp/charset.cc
no
checking for -exported_symbols_list linker flag... In file included from ../../libcpp/charset.cc:21:
In file included from ../../libcpp/system.h:279:
/usr/local/include/libintl.h:1089:34: error: expected unqualified-id
char *setlocale (int __category, const char *__locale)
                                 ^
/usr/local/include/libintl.h:1089:34: error: expected ')'
/usr/local/include/libintl.h:1089:7: note: to match this '('
char *setlocale (int __category, const char *__locale)
      ^
../../libcpp/system.h:275:38: note: expanded from macro 'setlocale'
# define setlocale(category, locale) (locale)
                                     ^
yes

hard to tell without looking at the code directly

[powerboat9]

It looks like everything would work if HAVE_SETLOCALE was defined, but I can't figure out where the configure script (?) is defining/not defining it