Makefile: Silence new GNU linker warnings

The next version of the linker will complain about rwx segments with
permissions and executable stacks:

 https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107
 https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=0d38576a34ec64a1b4500c9277a8e9d0f07e6774

These warnings are relevant for ELF binaries loaded by an operating
system linker, but do not make sense in the context of u-boot where the
objects are loaded by other means.

Disable the warnings using the following options:

 --no-warn-rwx-segments

  warning: u-boot has a LOAD segment with RWX permissions
  warning: u-boot-spl has a LOAD segment with RWX permissions

 --no-warn-execstack

  warning: arch/arm/lib/setjmp.o: missing .note.GNU-stack section implies executable stack
  NOTE: This behaviour is deprecated and will be removed in a future version of the linker

Signed-off-by: Joel Stanley <[email protected]>

Makefile

@@ -398,6 +398,8 @@ endif
 KBUILD_AFLAGS_KERNEL :=
 KBUILD_CFLAGS_KERNEL :=
 KBUILD_AFLAGS   := -D__ASSEMBLY__ $(call cc-option,-fno-PIE)
+KBUILD_LDFLAGS  := $(call ld-option, --no-warn-rwx-segments) \
+		   			$(call ld-option, --no-warn-execstack)
 KBUILD_AFLAGS_MODULE  := -DMODULE
 KBUILD_CFLAGS_MODULE  := -DMODULE
 KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds
@@ -417,6 +419,7 @@ export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
 export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV
 export CFLAGS_KASAN CFLAGS_UBSAN CFLAGS_KASAN_NOSANITIZE
 export CFLAGS_KCOV
+export KBUILD_LDFLAGS
 export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
 export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
 export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL