Search for directory containing build scripts

Currently only the source tree is "searched", but the template could
be expanded to look in another/more locations (or be specified
explicitly on the command-line with a --with-opm-macros= option)

configure

@@ -1,3 +1,35 @@
 #!/bin/sh
+# this file is supposed to be located in the source directory
+src_dir=$(dirname $0)
+
+# scan the arguments and set this if build macros could be specified
+mod_dir=
+for OPT in "$@"; do
+    case "$OPT" in
+        --with-opm-macros=*)
+            # remove everything before equal sign and assign the rest
+            mod_dir=${OPT#*=}
+            # tilde expansion; note that doing eval may have side effects
+            mod_dir=$(eval echo $mod_dir)
+            # absolute path
+            [ -d "$mod_dir" ] && mod_dir=$(cd $mod_dir ; pwd)
+            ;;
+    esac
+done
+
+# if it isn't specified, the look around in other known places
+conf_file=cmake/Scripts/configure
+if [ -z "$mod_dir" ]; then
+    if [ -r "$src_dir/$conf_file" ]; then
+        mod_dir="$src_dir"
+    fi
+fi
+
+# terminate with error message here if the module directory is not found
+if [ ! -r "$mod_dir/$conf_file" ]; then
+    echo Build macros not located in \"$mod_dir\", use --with-opm-macros= to specify! 1>&2
+    exit 1
+fi
+
 # forward to the corresponding script in the cmake/Scripts/ directory
-exec $(dirname $0)/cmake/Scripts/configure "$@"
+exec "$mod_dir/$conf_file" --src-dir="$src_dir" "$@"