package/libcpprestsdk: needs locale

locale_t is unconditionally used since version 2.3.0 and
https://github.com/microsoft/cpprestsdk/commit/814caa4c0a80ef223535446a274146bf46a5ef2b



Fixes:
 - No autobuilder failures

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>