feat(build): add support for new binutils versions

Users of GNU ld (BPF) from binutils 2.39+ will observe multiple instaces
of a new warning when linking the bl*.elf in the form:

  ld.bfd: warning: stm32mp1_helper.o: missing .note.GNU-stack section implies executable stack
  ld.bfd: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
  ld.bfd: warning: bl2.elf has a LOAD segment with RWX permissions
  ld.bfd: warning: bl32.elf has a LOAD segment with RWX permissions

These new warnings are enbaled by default to secure elf binaries:
 - https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107
 - https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=0d38576a34ec64a1b4500c9277a8e9d0f07e6774

Fix it in a similar way to what the Linux kernel does, see:

Following the reasoning there, we set "-z noexecstack" for all linkers
(although LLVM's LLD defaults to it) and optional add
--no-warn-rwx-segments since this a ld.bfd related.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Robert Schwebel <r.schwebel@pengutronix.de>
Change-Id: I9430f5fa5036ca88da46cd3b945754d62616b617
1 file changed