[Patch ARM] PR target/29693

[Ramana Radhakrishnan]

This fixes PR target/29693 by returning DWARF_FRAME_REGISTERS instead of 
calling gcc_unreachable.

Applied to trunk after bootstrap and regression testing on armhf.

Ramana

2015-06-25  Ramana Radhakrishnan  <ramana.radhakrish...@arm.com>

        PR target/29693
        * config/arm/arm.c (arm_dbx_register_number): Return
        DWARF_FRAME_REGISTERS by default.
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 09191e5..9f4e395 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -26389,7 +26389,7 @@ arm_dbx_register_number (unsigned int regno)
   if (IS_IWMMXT_REGNUM (regno))
     return 112 + regno - FIRST_IWMMXT_REGNUM;
 
-  gcc_unreachable ();
+  return DWARF_FRAME_REGISTERS;
 }
 
 /* Dwarf models VFPv3 registers as 32 64-bit registers.