Support structure offsets that are 512K or larger.

GDB computes structure byte offsets using a 32 bit integer.  And,
first it computes the offset in bits and then converts to bytes.  The
result is that any offset that if 512K bytes or larger overflows.
This patch changes GDB to use LONGEST for such calculations.

	PR gdb/17520 Structure offset wrong when 1/4 GB or greater.
	* c-lang.h: Change all parameters, variables, and struct or union
	members used as struct or union fie3ld offsets from int to
	LONGEST.
	* c-valprint.c: Likewise.
	* cp-abi.c: Likewise.
	* cp-abi.h: Likewise.
	* cp-valprint.c: Likewise.
	* d-valprint.c: Likewise.
	* dwarf2loc.c: Likewise.
	* eval.c: Likewise.
	* extension-priv.h: Likewise.
	* extension.c: Likewise.
	* extension.h: Likewise.
	* findvar.c: Likewise.
	* gdbtypes.h: Likewise.
	* gnu-v2-abi.c: Likewise.
	* gnu-v3-abi.c: Likewise.
	* go-valprint.c: Likewise.
	* guile/guile-internal.h: Likewise.
	* guile/scm-pretty-print.c: Likewise.
	* jv-valprint.c Likewise.
	* opencl-lang.c: Likewise.
	* p-lang.h: Likewise.
	* python/py-prettyprint.c: Likewise.
	* python/python-internal.h: Likewise.
	* spu-tdep.c: Likewise.
	* typeprint.c: Likewise.
	* valarith.c: Likewise.
	* valops.c: Likewise.
	* valprint.c: Likewise.
	* valprint.h: Likewise.
	* value.c: Likewise.
	* value.h: Likewise.
	* p-valprint.c: Likewise.
	* c-typeprint.c (c_type_print_base): When printing offset, use
	plongest, not %d.
	* gdbtypes.c (recursive_dump_type): Ditto.

gdb/gdbtypes.h

@@ -511,7 +511,7 @@ union field_location
      gdbarch_bits_big_endian=0 targets, it is the bit offset to
      the LSB.  */
 
-  int bitpos;
+  LONGEST bitpos;
 
   /* * Enum value.  */
   LONGEST enumval;