native tools must reliably use a native adjunct, even if that's inconvenient
While it is perhaps convenient for native tools to use updated versions
of certain things like libxml it is imperative that those versions are
_also_ build for the build machine.  Thus they need to be in the native
adjunct (even if that native adjunct is thus not /).
Fix the native adjunct to be rooted similarly to the adjunct proto (that
is, at /), and fix SMF to use it correctly

@@ -40,11 +40,11 @@
 ADJUNCT_PROTO=
 
 #
 # Adjunct for building things that run on the build machine.
 #
-NATIVE_ADJUNCT= /usr
+NATIVE_ADJUNCT= /
 
 #
 # RELEASE_BUILD should be cleared for final release builds.
 # NOT_RELEASE_BUILD is exactly what the name implies.
 #

@@ -557,11 +557,11 @@
 CPPFLAGS.first= # Please keep empty.  Only lower makefiles should set this.
 CPPFLAGS.master=$(DTEXTDOM) $(DTS_ERRNO) \
         $(ENVCPPFLAGS1) $(ENVCPPFLAGS2) $(ENVCPPFLAGS3) $(ENVCPPFLAGS4) \
         $(ADJUNCT_PROTO:%=-I%/usr/include)
 CPPFLAGS.native=$(ENVCPPFLAGS1) $(ENVCPPFLAGS2) $(ENVCPPFLAGS3) \
-                $(ENVCPPFLAGS4) -I$(NATIVE_ADJUNCT)/include
+                $(ENVCPPFLAGS4) -I$(NATIVE_ADJUNCT)/usr/include
 CPPFLAGS=       $(CPPFLAGS.first) $(CPPFLAGS.master)
 AS_CPPFLAGS=    $(CPPFLAGS.first) $(CPPFLAGS.master)
 JAVAFLAGS=      -source 1.6 -target 1.6 -Xlint:deprecation,-options
 
 #