patch 8.1.0664: configure "fail-if-missing" does not apply to enable-gui

Problem:    Configure "fail-if-missing" does not apply to the enable-gui
            argument. (Rhialto)
Solution:   Make configure fail if a GUI was specifified and "fail-if-missing"
            is enabled and the GUI test fails.

src/auto/configure

@@ -9115,10 +9115,9 @@ if test "x$QNX" = "xyes" -a "x$with_x" = "xno" ; then
     no)		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no GUI support" >&5
 $as_echo "no GUI support" >&6; }
 		SKIP_PHOTON=YES ;;
-    yes|"")	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes - automatic GUI support" >&5
+    yes|""|auto) { $as_echo "$as_me:${as_lineno-$LINENO}: result: automatic GUI support" >&5
-$as_echo "yes - automatic GUI support" >&6; } ;;
+$as_echo "automatic GUI support" >&6; }
-    auto)	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: auto - automatic GUI support" >&5
+    		gui_auto=yes ;;
-$as_echo "auto - automatic GUI support" >&6; } ;;
     photon)	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: Photon GUI support" >&5
 $as_echo "Photon GUI support" >&6; } ;;
     *)		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: Sorry, $enable_gui GUI is not supported" >&5
@@ -9133,7 +9132,8 @@ elif test "x$MACOS_X" = "xyes" -a "x$with_x" = "xno" ; then
 $as_echo "no GUI support" >&6; }
 		SKIP_CARBON=YES ;;
     yes|"")	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes - automatic GUI support" >&5
-$as_echo "yes - automatic GUI support" >&6; } ;;
+$as_echo "yes - automatic GUI support" >&6; }
+    		gui_auto=yes ;;
     auto)	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: auto - Carbon GUI is outdated - disable GUI support" >&5
 $as_echo "auto - Carbon GUI is outdated - disable GUI support" >&6; }
 		SKIP_CARBON=YES ;;
@@ -9151,6 +9151,7 @@ else
 $as_echo "no GUI support" >&6; } ;;
     yes|""|auto)	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes/auto - automatic GUI support" >&5
 $as_echo "yes/auto - automatic GUI support" >&6; }
+		gui_auto=yes
 		SKIP_GTK2=
 		SKIP_GNOME=
 		SKIP_MOTIF=
@@ -9582,6 +9583,9 @@ $as_echo "no" >&6; }
       GTK_CFLAGS=""
       GTK_LIBS=""
       :
+      if test "$fail_if_missing" = "yes" -a "X$gui_auto" != "Xyes"; then
+	as_fn_error $? "could not configure GTK" "$LINENO" 5
+      fi
     }
     fi
   }
@@ -9933,6 +9937,9 @@ $as_echo "no" >&6; }
       GTK_CFLAGS=""
       GTK_LIBS=""
       :
+      if test "$fail_if_missing" = "yes" -a "X$gui_auto" != "Xyes"; then
+	as_fn_error $? "could not configure GTK" "$LINENO" 5
+      fi
     }
     fi
   }

src/configure.ac

@@ -2366,8 +2366,8 @@ if test "x$QNX" = "xyes" -a "x$with_x" = "xno" ; then
   case "$enable_gui_canon" in
     no)		AC_MSG_RESULT(no GUI support)
 		SKIP_PHOTON=YES ;;
-    yes|"")	AC_MSG_RESULT(yes - automatic GUI support) ;;
+    yes|""|auto) AC_MSG_RESULT(automatic GUI support)
-    auto)	AC_MSG_RESULT(auto - automatic GUI support) ;;
+    		gui_auto=yes ;;
     photon)	AC_MSG_RESULT(Photon GUI support) ;;
     *)		AC_MSG_RESULT([Sorry, $enable_gui GUI is not supported])
 		SKIP_PHOTON=YES ;;
@@ -2378,7 +2378,8 @@ elif test "x$MACOS_X" = "xyes" -a "x$with_x" = "xno" ; then
   case "$enable_gui_canon" in
     no)		AC_MSG_RESULT(no GUI support)
 		SKIP_CARBON=YES ;;
-    yes|"")	AC_MSG_RESULT(yes - automatic GUI support) ;;
+    yes|"")	AC_MSG_RESULT(yes - automatic GUI support)
+    		gui_auto=yes ;;
     auto)	AC_MSG_RESULT(auto - Carbon GUI is outdated - disable GUI support)
 		SKIP_CARBON=YES ;;
     carbon)	AC_MSG_RESULT(Carbon GUI support) ;;
@@ -2391,6 +2392,7 @@ else
   case "$enable_gui_canon" in
     no|none)	AC_MSG_RESULT(no GUI support) ;;
     yes|""|auto)	AC_MSG_RESULT(yes/auto - automatic GUI support)
+		gui_auto=yes
 		SKIP_GTK2=
 		SKIP_GNOME=
 		SKIP_MOTIF=
@@ -2638,6 +2640,9 @@ return 1;
       GTK_CFLAGS=""
       GTK_LIBS=""
       ifelse([$3], , :, [$3])
+      if test "$fail_if_missing" = "yes" -a "X$gui_auto" != "Xyes"; then
+	AC_MSG_ERROR([could not configure GTK])
+      fi
     }
     fi
   }

src/version.c

@@ -799,6 +799,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    664,
 /**/
     663,
 /**/