linker: sort sections by alignment

This turns on the linker flag to sort sections by alignment
in decreasing size of symbols. This helps to minimize
padding between symbols.

This also adds the linker options to sort common symbols by
alignment in descending to minimize the need for padding.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

Author: dcpleung

CMakeLists.txt

@@ -384,6 +384,13 @@ zephyr_ld_options(
   ${LINKERFLAGPREFIX},--build-id=none
   )
 
+# Sort the common symbols and each input section by alignment
+# in descending order to minimize padding between these symbols.
+zephyr_ld_options(
+  ${LINKERFLAGPREFIX},--sort-common=descending
+  ${LINKERFLAGPREFIX},--sort-section=alignment
+  )
+
 get_property(TOPT GLOBAL PROPERTY TOPT)
 set_ifndef(  TOPT -T)