AM Conditional for SUBDIRS

[Vikram Ambrose]

I have a problem trying to conditional include a subdir into a build 
configuration or not.

I have tried two things.
1)
-------------------------------------------------
SUBDIRS = pkgA pkgB

if BUILD_pkgC
  SUBDIRS += pkgC
endif
-------------------------------------------------


2)
-------------------------------------------------
SUBDIRS = pkgA pkgB $(extra_pkgs)

extra_pkgs =
if BUILD_pkgC
  extra_pkgs += pkgC
endif
-------------------------------------------------


Both of which work, for make; make install; make clean; but when i try 
to make dist or make distclean, they fail. I do a test in configure.ac 
to conditional set AC_CONFIG_FILES([pkgc/Makefile])

How do I do this properly?

Vikram