[PATCH] Remove nested feature sections

The {BEGIN,END}_FTR_SECTION asm macros used in ppc64 to nop out
sections of code at runtime cannot be nested.  However, we do nest
them in hash_low.S.  We get away with it there, because there is
nothing between the BEGIN markers for each section.  However, that's
confusing to someone reading the code.

This patch removes the nested ifset and ifclr feature sections,
replacing them with a single feature section in the full mask/value
form.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>