More informative messages about missing package

autogen.sh

@@ -1,15 +1,35 @@
 #! /bin/sh
 
-if [ -x "`which autoreconf 2>/dev/null`" ] ; then
-  exec autoreconf -ivf
-fi
-
 if glibtoolize --version > /dev/null 2>&1; then
   LIBTOOLIZE='glibtoolize'
 else
   LIBTOOLIZE='libtoolize'
 fi
 
+if [ ! -x "`which $LIBTOOLIZE 2>/dev/null`" ] ; then
+  echo "libtool is required, but wasn't found on this system"
+  exit 1
+fi
+
+if [ ! -x "`which autoconf 2>/dev/null`" ] ; then
+  echo "autoconf is required, but wasn't found on this system"
+  exit 1
+fi
+
+if [ ! -x "`which automake 2>/dev/null`" ] ; then
+  echo "automake is required, but wasn't found on this system"
+  exit 1
+fi
+
+if [ ! -x "`which pkg-config 2>/dev/null`" ] ; then
+  echo "pkg-config is required, but wasn't found on this system"
+  exit 1
+fi
+
+if [ -x "`which autoreconf 2>/dev/null`" ] ; then
+  exec autoreconf -ivf
+fi
+
 $LIBTOOLIZE && \
 aclocal && \
 automake --add-missing --force-missing --include-deps && \