Put arm/aarch64 assembly functions in their own section.

This change causes each global arm or aarch64 asm function to be put
into its own section by default. This matches the behaviour of the
-ffunction-sections option to GCC and allows the --gc-sections option to
the linker to discard unused asm functions on a function-by-function
basis.

Sometimes several asm functions will share the same data an, in that
situation, the data is put into the section of one of the functions and
the section of the other function is merged with the added
“.global_with_section” directive.

Change-Id: I12c9b844d48d104d28beb816764358551eac4456
Reviewed-on: https://boringssl-review.googlesource.com/6003
Reviewed-by: Adam Langley <agl@google.com>
7 files changed