build system: make PER_USER_DIRECTORY and PER_MACHINE_DIRECTORY overridable from local.config

The CPP macros setting them were defined too high in Makefile.conf to take
local.config into account.  This change moves the definition down.

Makefile.conf

@@ -297,16 +297,6 @@ SEQUOIA_INC=
 #    EXTRA_MACROS=-DDEFAULT_KEYSERVER=\"default-server.org\" -DCRASHDUMP_DEFAULT_LINES=23
 EXTRA_MACROS=
 
-# Notice the single quotes below: since user definitions can contain dollar
-# signs it is important to prevent their expansion: shell variable references
-# here must be expanded at run time, and not at compile time.
-ifdef PER_USER_DIRECTORY
-       EXTRA_MACROS+= -DPER_USER_DIRECTORY='"$(PER_USER_DIRECTORY)"'
-endif
-ifdef PER_MACHINE_DIRECTORY
-       EXTRA_MACROS+= -DPER_MACHINE_DIRECTORY='"$(PER_MACHINE_DIRECTORY)"'
-endif
-
 CFLAGS+=$(EXTRA_MACROS)
 CXXFLAGS+=$(EXTRA_MACROS)
 
@@ -335,6 +325,16 @@ endif
 
 ######### Post processing assignments ########
 
+# Notice the single quotes below: since user definitions can contain dollar
+# signs it is important to prevent their expansion: shell variable references
+# here must be expanded at run time, and not at compile time.
+ifdef PER_USER_DIRECTORY
+       EXTRA_MACROS+= -DPER_USER_DIRECTORY='"$(PER_USER_DIRECTORY)"'
+endif
+ifdef PER_MACHINE_DIRECTORY
+       EXTRA_MACROS+= -DPER_MACHINE_DIRECTORY='"$(PER_MACHINE_DIRECTORY)"'
+endif
+
 # If sequoia has been set up and the SEQUOIA flags aren't defined, set them up.
 # Otherwise, add them to the CFLAGS/CXXFLAGS/LDFLAGS and library/include variables
 ifeq ($(OPENPGP),SEQUOIA)