Update gdb/NEWS in preparation for GDB 7.8 release.

gdb/ChangeLog:

	* NEWS: Change "Changes since GDB 7.7" into "Changes in GDB 7.8".
Set GDB version number to 7.8.

gdb/ChangeLog:

	* version.in: Set GDB version number to 7.8.
Document the GDB 7.8 release in gdb/ChangeLog

gdb/ChangeLog:

	GDB 7.8 released.
Bump GDB version number to 7.8.0.DATE-cvs.

gdb/ChangeLog:

	* version.in: Set GDB version number to 7.8.0.DATE-cvs.
Automatic date update in version.in
Automatic date update in version.in
Merge remote-tracking branch 'gnu/gdb-7.8-branch' into 7.8