contrib/buildsystems: redirect stderr into the correct directory

The script assumes that we're in the top-level directory of the
checkout. That does not need to be true.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

contrib/buildsystems/engine.pl

@@ -82,7 +82,7 @@ sub showUsage
 # Capture the make dry stderr to file for review (will be empty for a release build).
 
 my $ErrsFile = "msvc-build-makedryerrors.txt";
-@makedry = `cd $git_dir && make -n MSVC=1 V=1 2>$ErrsFile` if !@makedry;
+@makedry = `make -C $git_dir -n MSVC=1 V=1 2>$ErrsFile` if !@makedry;
 # test for an empty Errors file and remove it
 unlink $ErrsFile if -f -z $ErrsFile;