Fix -Wundef warnings for SHARED

Fix -Wundef warnings for SHARED

The definition of SHARED is tested with #ifdef pretty much everywhere
apart from these few places. The tlsdesc.c code seems to be copy and
pasted to a few architectures and there is one instance in the hppa
startup code.

ChangeLog:

2014-07-09  Will Newton  <will.newton@linaro.org>

	* sysdeps/aarch64/tlsdesc.c (_dl_unmap): Test SHARED with #ifdef.
	* sysdeps/arm/tlsdesc.c (_dl_unmap): Likewise.
	* sysdeps/i386/tlsdesc.c (_dl_unmap): Likewise.
	* sysdeps/x86_64/tlsdesc.c (_dl_unmap): Likewise.
	* sysdeps/hppa/start.S (_start): Likewise.