Update gphoto2 help messages

configure

@@ -17,10 +17,10 @@ ac_help="$ac_help
   --enable-warnings       turn on tons of compiler warnings (GCC only) 
                           [default=yes]"
 ac_help="$ac_help
-  --with-gphoto2=DIR      specify the top-level GPHOTO2 directory 
+  --with-gphoto2[=DIR]    specify the top-level GPHOTO2 directory 
                           [default=/usr/local]"
 ac_help="$ac_help
-  --with-ptal=DIR         specify the top-level PTAL directory 
+  --with-ptal[=DIR]       specify the top-level PTAL directory 
                           [default=/usr/local]"
 ac_help="$ac_help
   --enable-shared[=PKGS]  build shared libraries [default=yes]"
@@ -3047,9 +3047,9 @@ if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
   cat >> confdefs.h <<EOF
 #define $ac_tr_hdr 1
 EOF
- echo $ac_n "checking for gp_init in -lgphoto2""... $ac_c" 1>&6
-echo "configure:3052: checking for gp_init in -lgphoto2" >&5
-ac_lib_var=`echo gphoto2'_'gp_init | sed 'y%./+-%__p_%'`
+ echo $ac_n "checking for gp_camera_init in -lgphoto2""... $ac_c" 1>&6
+echo "configure:3052: checking for gp_camera_init in -lgphoto2" >&5
+ac_lib_var=`echo gphoto2'_'gp_camera_init | sed 'y%./+-%__p_%'`
 if eval "test \"`echo '$''{'ac_cv_lib_$ac_lib_var'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -3061,10 +3061,10 @@ cat > conftest.$ac_ext <<EOF
 /* Override any gcc2 internal prototype to avoid an error.  */
 /* We use char because int might match the return type of a gcc2
     builtin and then its argument prototype would still apply.  */
-char gp_init();
+char gp_camera_init();
 
 int main() {
-gp_init()
+gp_camera_init()
 ; return 0; }
 EOF
 if { (eval echo configure:3071: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then