sandbox: Fix building with LLVM

- The macro __BIGGEST_ALIGNMENT__ is gcc-specific.  If it is not defined
  we'll just assume 16.  This is correct for at least the common cases
  and LLVM does not provide an equivalent macro.
- When linking U-Boot we're passing -T to the linker, and while gcc will
  just pass this along with LLVM we need to be specific.

Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/config.mk b/arch/sandbox/config.mk
index b05a90f..16fd6d50 100644
--- a/arch/sandbox/config.mk
+++ b/arch/sandbox/config.mk
@@ -16,7 +16,7 @@
 endif
 endif
 
-cmd_u-boot__ = $(CC) -o $@ -T u-boot.lds \
+cmd_u-boot__ = $(CC) -o $@ -Wl,-T u-boot.lds \
 	-Wl,--start-group $(u-boot-main) -Wl,--end-group \
 	$(PLATFORM_LIBS) -Wl,-Map -Wl,u-boot.map