Fix gdb.texinfo build

Fix gdb.texinfo build

Commit b4be1b064860 ("Fix MI output for multi-location breakpoints")
broke the build of gdb.texinfo.  The problem is simply the use of "@end
@table", which should be "@end table".

The error was:

    /home/smarchi/src/binutils-gdb/gdb/doc/gdb.texinfo:27870: warning: @table should not appear in @end
    /home/smarchi/src/binutils-gdb/gdb/doc/gdb.texinfo:27870: table requires an argument: the formatter for @item
    /home/smarchi/src/binutils-gdb/gdb/doc/gdb.texinfo:27870: no matching `@end table'
    /home/smarchi/src/binutils-gdb/gdb/doc/gdb.texinfo:27870: bad argument to @end: @table
    /home/smarchi/src/binutils-gdb/gdb/doc/gdb.texinfo:27867: warning: @table has text but no @item
    /home/smarchi/src/binutils-gdb/gdb/doc/gdb.texinfo:27879: @node seen before @end table

gdb/doc/ChangeLog:

	* gdb.texinfo (GDB/MI Development and Front Ends): Fix closing
	of table, "@end @table" -> "@end table".