Fix bug where malloc() doesn't return a null pointer

The malloc() function doesn't return a null pointer for too large requests. The cause is that the _sbrk() function isn't linked from the Renesas FSP as it should be, but instead from the Arm toolchain. This fix makes sure that the correct version of _sbrk() is linked.

Author: alrvid

platform.txt

@@ -76,7 +76,7 @@ recipe.S.o.pattern="{compiler.path}{compiler.S.cmd}" {compiler.S.flags} -DARDUIN
 recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}"
 
 ## Combine gc-sections, archives, and objects
-recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} {build.extra_flags} -o "{build.path}/{build.project_name}.elf" "-L{build.path}" "-L{build.variant.path}" "-T{build.variant.path}/fsp.ld" {object_files} -Wl,--start-group {compiler.fsp} "{build.path}/{archive_file}" {compiler.fsp.extra_ldflags} {compiler.libraries.ldflags} -Wl,--end-group "-Wl,-Map,{build.path}/{build.project_name}.map"
+recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} {build.extra_flags} -o "{build.path}/{build.project_name}.elf" "-L{build.path}" "-L{build.variant.path}" "-T{build.variant.path}/fsp.ld" {object_files} -Wl,--whole-archive -Wl,--start-group {compiler.fsp} "{build.path}/{archive_file}" -Wl,--no-whole-archive {compiler.fsp.extra_ldflags} {compiler.libraries.ldflags} -Wl,--end-group "-Wl,-Map,{build.path}/{build.project_name}.map"
 
 ## Create output (bin file)
 recipe.objcopy.bin.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.bin.flags} {compiler.elf2hex.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.bin"