(maint) System Locales fails regex backup

In case the locales on the system fails(due to gconv, or somethingelse),
leatherman will use boost::format and boost::regex, to create %N%style
formatting. 'regex' is only included in CMakeLists.txt if localesare
enabled, but if they fail, 'regex' will be required

This PR adds 'regex' to BOOST_COMPONENTS even if leatherman useslocales,
as an extra check in case the locales are enabled but fail.

CMakeLists.txt

@@ -37,7 +37,7 @@ endif()
 include(leatherman)
 
 if(LEATHERMAN_USE_LOCALES)
-    set(BOOST_COMPONENTS locale)
+    set(BOOST_COMPONENTS locale regex)
 else()
     set(BOOST_COMPONENTS regex)
 endif()