Change field separator in gdbarch.sh

Change field separator in gdbarch.sh

The fields in the description of the gdbarch interface are separated
using colons.  That becomes a problem if we want to use things like
std::vector in it. This patch changes the field separator to use
semicolons instead.

I think there's very little chance we'll ever want to use a semicolon in
one of the fields, but if you think another character would be more
appropriate, let me know.

gdb/ChangeLog:

	* gdbarch.sh: Use semi-colon as field separator instead of colon.
	* gdbarch.h: Re-generate.