Try to find seamonkey-config too.

TODO: test for xpidl in /usr/lib{,64}/seamonkey too.

configure.ac

@@ -5162,6 +5162,9 @@ then
   then
     AC_PATH_PROG(MOZILLA_CONFIG, mozilla-config, no)
     if test "${MOZILLA_CONFIG}" = "no"
+    then
+      AC_PATH_PROG(SEAMONKEY_CONFIG, seamonkey-config, no)
+      if test "${SEAMONKEY_CONFIG}" = "no"
       then
         AC_PATH_PROG(XULRUNNER_CONFIG, xulrunner-config, no)
         if test "${XULRUNNER_CONFIG}" = "no"
@@ -5171,6 +5174,9 @@ then
           have_xul=true
           MOZILLA_CONFIG="${XULRUNNER_CONFIG}"
         fi
+      else
+        MOZILLA_CONFIG="${SEAMONKEY_CONFIG}"
+      fi
     fi
     
     if ${MOZILLA_CONFIG} --defines | grep -q 'MOZ_X11=1'; then