Make sure $PERL_PATH is defined when the test suite is run.

Some test scripts run Perl scripts as if they were git-* scripts, and
thus need to use the same perl that will be put in the shebang line of
git*.perl commands. $PERL_PATH therefore needs to be used instead of
a bare "perl".

The tests can fail if another perl is found in $PATH before the one
defined in $PERL_PATH.

Example test failure caused by this: the perl defined in $PERL_PATH has
Error.pm installed, and therefore the Git.pm's Makefile.PL doesn't install
the private copy. The perl from $PATH doesn't have Error.pm installed, and
all git*.perl scripts invoked during the test will fail loading Error.pm.

Makefile patch by Jeff King <peff@peff.net>.

Signed-off-by: Philippe Bruhat (BooK) <book@cpan.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t9400-git-cvsserver-server.sh b/t/t9400-git-cvsserver-server.sh
index 64f947d..c2ec3cb 100755
--- a/t/t9400-git-cvsserver-server.sh
+++ b/t/t9400-git-cvsserver-server.sh
@@ -20,7 +20,7 @@
     say 'skipping git-cvsserver tests, cvs not found'
     test_done
 fi
-perl -e 'use DBI; use DBD::SQLite' >/dev/null 2>&1 || {
+"$PERL_PATH" -e 'use DBI; use DBD::SQLite' >/dev/null 2>&1 || {
     say 'skipping git-cvsserver tests, Perl SQLite interface unavailable'
     test_done
 }
diff --git a/t/t9401-git-cvsserver-crlf.sh b/t/t9401-git-cvsserver-crlf.sh
index aca40c1..40637d6 100755
--- a/t/t9401-git-cvsserver-crlf.sh
+++ b/t/t9401-git-cvsserver-crlf.sh
@@ -57,7 +57,7 @@
     say 'skipping git-cvsserver tests, perl not available'
     test_done
 fi
-perl -e 'use DBI; use DBD::SQLite' >/dev/null 2>&1 || {
+"$PERL_PATH" -e 'use DBI; use DBD::SQLite' >/dev/null 2>&1 || {
     say 'skipping git-cvsserver tests, Perl SQLite interface unavailable'
     test_done
 }
diff --git a/t/t9700-perl-git.sh b/t/t9700-perl-git.sh
index 4eb7d3f..8686086 100755
--- a/t/t9700-perl-git.sh
+++ b/t/t9700-perl-git.sh
@@ -11,7 +11,7 @@
 	test_done
 fi
 
-perl -MTest::More -e 0 2>/dev/null || {
+"$PERL_PATH" -MTest::More -e 0 2>/dev/null || {
 	say "Perl Test::More unavailable, skipping test"
 	test_done
 }
@@ -48,6 +48,6 @@
 
 test_external_without_stderr \
     'Perl API' \
-    perl "$TEST_DIRECTORY"/t9700/test.pl
+    "$PERL_PATH" "$TEST_DIRECTORY"/t9700/test.pl
 
 test_done