target: Add 64-bit target address support

Define a target_addr_t type to support 32-bit and 64-bit addresses at
the same time. Also define matching TARGET_PRI*ADDR format macros as
well as a convenient TARGET_ADDR_FMT.

In targets that are 32-bit (avr32, nds32, arm7/9/11, fm4, xmc1000)
be least invasive by leaving the formatting unchanged apart from the
type;
for generic code adopt TARGET_ADDR_FMT as unified address format.

Don't silently change gdb formatting here, leave that to later.

Add COMMAND_PARSE_ADDRESS() macro to abstract the address type.
Implement it using its own parse_target_addr() function, in the hopes
of catching pointer type mismatches better.

Add '--disable-target64' configure option to revert to previous 32-bit
target address behavior.

Change-Id: I2e91d205862ceb14f94b3e72a7e99ee0373a85d5
Signed-off-by: Dongxue Zhang <elta.era@gmail.com>
Signed-off-by: David Ung <david.ung.42@gmail.com>
[AF: Default to enabling (Paul Fertser), rename macros, simplify]
Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Matthias Welwarsky <matthias.welwarsky@sysgo.com>