configure.sh: Look for AFDKO.

Debian-like distributions install AFDKO's executables into libexec and
provide an `afdko` helper to call them.

Python's pip installs the executables in bin.

Let's support both.

configure.sh

@@ -46,6 +46,17 @@ dependency_command() {
     fi
 }
 
+dependency_afdko() {
+    if command -v makeotf &> /dev/null; then
+        AFDKO_VERB=
+    elif command -v afdko &> /dev/null; then
+        AFDKO_VERB=afdko
+    else
+        err "Couldn't find 'afdko'. Install it and make sure that 'makeotf' is in your PATH or 'afdko makeotf' works."
+            MISSING_DEPENDENCIES=1
+    fi
+}
+
 #
 # Configure
 #
@@ -90,6 +101,8 @@ function configure() {
   dependency_command git
   dependency_command python3
 
+  dependency_afdko
+
   if [ "$MISSING_DEPENDENCIES" -ne 0 ]; then
       die "Missing dependencies, cannot continue."
   fi
@@ -113,6 +126,8 @@ function configure() {
       echo "DOCKER_OPTS := $arg_docker_opts"
     fi
 
+    echo "AFDKO_VERB := $AFDKO_VERB"
+
     # Include base
     echo ""
     echo "include \$(SRCDIR)/build/makefile_base.mak"