Use $DJDIR rather than $DJGPP to detect running on DJGPP.

[Ralf Wildenhues]

I'm applying this patch to maint, in accordance with similar changes to
Autoconf done a few weeks ago.  I haven't actually tried to build and
test git Automake on DJGPP, but $DJGPP is set in the environment even
under my MinGW/MSYS and this caused bootstrap to fail.

Cheers,
Ralf

    Use $DJDIR rather than $DJGPP to detect running on DJGPP.
    
    * automake.in (Language): Use $ENV{'DJDIR'} for the
    $ENV{'SHELL'} override.
    * bootstrap: Use $DJDIR for setting BOOTSTRAP_SHELL, to fix
    bootstrapping under MinGW when $DJGPP has been set.

diff --git a/automake.in b/automake.in
index 871c98e..e934c5f 100755
--- a/automake.in
+++ b/automake.in
@@ -41,7 +41,7 @@ BEGIN
   # it turns up other systems need the same thing.  After all,
   # if SHELL is used, ./configure's SHELL is always better than
   # the user's SHELL (which may be something like tcsh).
-  $ENV{'SHELL'} = '@SHELL@' if exists $ENV{'DJGPP'};
+  $ENV{'SHELL'} = '@SHELL@' if exists $ENV{'DJDIR'};
 }
 
 use Automake::Struct;
diff --git a/bootstrap b/bootstrap
index fff40d5..2a86345 100755
--- a/bootstrap
+++ b/bootstrap
@@ -61,7 +61,7 @@ PERL_THREADS=0
 # Override SHELL.  This is required on DJGPP so that Perl's system()
 # uses bash, not COMMAND.COM which doesn't quote arguments properly.
 # It's not used otherwise.
-if test -n "$DJGPP"; then
+if test -n "$DJDIR"; then
     BOOTSTRAP_SHELL=/dev/env/DJDIR/bin/bash.exe
 else
     BOOTSTRAP_SHELL=/bin/sh