config: Split debug build from debug symbols

config: Split debug build from debug symbols

RPM based packaging systems expect binaries to have debug symbols which get
placed in a separate debuginfo RPM.

Split the concept of a debug build up so that binaries can be built with
debugging symbols without having the other gubbins which $(debug) implies, most
notibly frame pointers.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>