Inline ldrex/strex for thumb2, remove ARMv5 remnants.

We assume ARMv7 which with thumb2 has ldrex/strex operations that may be
inlined if -mthumb is defined.
Remove remnants of ARMv5 support.

Change-Id: I9bb9525ae6ff4816ba391115019d841f63c12348
Tidy up long lines

Change-Id: I22d90a343c351b90f460b8810bfb4bd28dc0792d