[Automake-NG] [FYI] [ng] header vars: fix comment on why DESTDIR is not explicitly initialized

[Stefano Lattarini]

* lib/am/header-vars.am (DESTDIR): It's not because we want to allow
it to be defined from the environment, for compatibility with mainline
Automake.  For better clarity, define an (empty) default with the line
"DESTDIR ?=", instead that with the commend-out definition "# DESTDIR=".

Signed-off-by: Stefano Lattarini <address@hidden>
---
 lib/am/header-vars.am | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/lib/am/header-vars.am b/lib/am/header-vars.am
index a27a8fb..22d6234 100644
--- a/lib/am/header-vars.am
+++ b/lib/am/header-vars.am
@@ -119,13 +119,9 @@ am__ensure_target_dir_exists = $(call 
am__ensure_dir_exists,$(@D))
 am.vpath.rewrite = \
   $(firstword $(wildcard $(strip $(1))) $(srcdir)/$(strip $(1)))
 
-## We used to define this.  However, we don't because vendor makes
-## (e.g., Solaris, Irix) won't correctly propagate variables that are
-## defined in Makefile.  This particular variable can't be correctly
-## defined by configure (at least, not the current configure), so we
-## simply avoid defining it to allow the user to use this feature with
-## a vendor make.
-## DESTDIR =
+# We want ithis to be overridable from the environment, for better
+# compatibility with mainline Automake.
+DESTDIR ?=
 
 ## Tell whether make is running in "dry mode".  It is either 'true' or
 ## 'false', so that it can be easily used in shell code as well as in
-- 
1.7.12.rc0