kbuild: introduce new option to enhance section mismatch analysis

Setting the option DEBUG_SECTION_MISMATCH will
report additional section mismatch'es but this
should in the end makes it possible to get rid of
all of them.

See help text in lib/Kconfig.debug for details.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index db38ef4..67fb453 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -103,6 +103,10 @@
   endif
 endif
 
+# Do section mismatch analysis for each module/built-in.o
+ifdef CONFIG_DEBUG_SECTION_MISMATCH
+  cmd_secanalysis = ; scripts/mod/modpost $@
+endif
 
 # Compile C sources (.c)
 # ---------------------------------------------------------------------------
@@ -268,7 +272,8 @@
 quiet_cmd_link_o_target = LD      $@
 # If the list of objects to link is empty, just create an empty built-in.o
 cmd_link_o_target = $(if $(strip $(obj-y)),\
-		      $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^),\
+		      $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^) \
+		      $(cmd_secanalysis),\
 		      rm -f $@; $(AR) rcs $@)
 
 $(builtin-target): $(obj-y) FORCE
@@ -316,7 +321,7 @@
 $($(subst $(obj)/,,$(@:.o=-y)))), $^)
  
 quiet_cmd_link_multi-y = LD      $@
-cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps)
+cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
 
 quiet_cmd_link_multi-m = LD [M]  $@
 cmd_link_multi-m = $(cmd_link_multi-y)