* arm-tdep.h (struct gdbarch_tdep): Add fields for breakpoint

* arm-tdep.h (struct gdbarch_tdep): Add fields for breakpoint
descriptions.
* arm-tdep.c (arm_default_arm_le_breakpoint)
(arm_default_arm_be_breakpoint, arm_default_thumb_le_breakpoint)
(arm_default_thumb_be_breakpoint): New.  Initialize them from
traditional breakpoint defines.
(arm_breakpoint_from_pc): Use new gdbarch_tdep entries.
(arm_gdbarch_init): Initialize new breakpoint variables.
* arm-linux-tdep.c (arm_linux_arm_le_breakpoint): New.
(arm_linux_init_abi): Initialize linux-specific breakpoint.
* armnbsd-tdep.c (arm_nbsd_arm_le_breakpoint): New.
(arm_netbsd_aout_init_abi, arm_netbsd_elf_init_abi): Split common
code out to ...
(arm_netbsd_init_abi_common): ... here; new function.
* config/arm/tm-arm.h (ARM_LE_BREAKPOINT, ARM_BE_BREAKPOINT)
(THUMB_LE_BREAKPOINT, THUMB_BE_BREAKPOINT): Delete.
* config/arm/tm-linux.h (ARM_LE_BREAKPOINT): Delete.
* config/arm/tm-nbsd.h (ARM_LE_BREAKPOINT): Delete.