build(bl2u): sort sections by alignment by default

This change forces LD to sort all input sections by alignment when
allocating them within an output section. This is done in some places
explicitly in the linker scripts today, but this makes sure we don't
miss any easy targets.

Change-Id: I2745327ed106295e0e0d3a54b3096514a1403c3c
Signed-off-by: Chris Kay <chris.kay@arm.com>

bl2u/bl2u.mk

@@ -13,3 +13,9 @@ BL2U_SOURCES		+=	common/aarch64/early_exceptions.S
 endif
 
 BL2U_DEFAULT_LINKER_SCRIPT_SOURCE := bl2u/bl2u.ld.S
+
+ifneq ($(findstring gcc,$(notdir $(LD))),)
+        BL2U_LDFLAGS	+=	-Wl,--sort-section=alignment
+else ifneq ($(findstring ld,$(notdir $(LD))),)
+        BL2U_LDFLAGS	+=	--sort-section=alignment
+endif