Nvptx's mkoffload.cc contains 14 'fatal_error' calls and one 'warning_at' call,
which stands out more clearly (color, bold) when enabling
   diagnostic_color_init
which this patch does. — Additionally, the call gcc_init_libintl permits that
the already translated error messages also show up as translation.

OK for mainline?

Tobias

PS: Example: 'nvptx mkoffload:' is bold and 'fatal error:' is in red
in English and some language variants.

nvptx mkoffload: fatal error: COLLECT_GCC must be set.
nvptx mkoffload: 致命的エラー: COLLECT_GCC must be set.
nvptx mkoffload: erreur fatale: COLLECT_GCC doit être défini.
nvptx mkoffload: schwerwiegender Fehler: COLLECT_GCC muss gesetzt sein.

(BTW: It looks as if many languages did not translate the error string
itself, e.g. jp or zh or pl or zh_TW/zh_CN or fi or ...)