make 'configure --with-gssapi=yes' fatal if support is not found

(cherry picked from commit e420078c)

configure

@@ -1771,7 +1771,7 @@ Optional Packages:
   --with-geoip=PATH       Build with GeoIP support (yes|no|path)
   --with-gssapi=PATH|/path/krb5-config
                           Specify path for system-supplied GSSAPI
-                          [default=yes]
+                          [default=auto]
   --with-randomdev=PATH   Specify path for random device
   --with-locktype=ARG     Specify mutex lock type (adaptive or standard)
   --with-libtool          use GNU libtool
@@ -14870,7 +14870,7 @@ $as_echo_n "checking for GSSAPI library... " >&6; }
 if test "${with_gssapi+set}" = set; then :
   withval=$with_gssapi; use_gssapi="$withval"
 else
-  use_gssapi="yes"
+  use_gssapi="auto"
 fi
 
 
@@ -15010,7 +15010,7 @@ esac
 
 case "$host" in
 *darwin*)
-	if test "yes" = "$use_gssapi"
+	if test "yes" = "$use_gssapi" -o "auto" = "$use_gssapi"
 	then
 		use_gssapi=framework
 	fi
@@ -15023,7 +15023,7 @@ esac
 # for the specification of gssapi and krb5 headers in different locations,
 # which probably ought to be fixed although fixing might raise the issue of
 # trying to build with incompatible versions of gssapi and krb5.
-if test "yes" = "$use_gssapi"
+if test "yes" = "$use_gssapi" -o "auto" = "$use_gssapi"
 then
 	# first, deal with the obvious
 	if test \( -f /usr/include/kerberosv5/krb5.h -o \
@@ -15047,8 +15047,11 @@ then
 				break
 			fi
 		fi
-		use_gssapi="no"
 	    done
+	    if test "auto" = "$use_gssapi"
+	    then
+		use_gssapi="no"
+	    fi
 	fi
 fi
 

configure.ac

@@ -804,8 +804,8 @@ AC_MSG_CHECKING(for GSSAPI library)
 AC_ARG_WITH(gssapi,
 	    AS_HELP_STRING([--with-gssapi=[PATH|[/path/]krb5-config]],
 			   [Specify path for system-supplied GSSAPI
-				[default=yes]]),
-	    use_gssapi="$withval", use_gssapi="yes")
+				[default=auto]]),
+	    use_gssapi="$withval", use_gssapi="auto")
 
 # first try using krb5-config, if that does not work then fall back to "yes" method.
 
@@ -859,7 +859,7 @@ esac
 
 case "$host" in
 *darwin*)
-	if test "yes" = "$use_gssapi"
+	if test "yes" = "$use_gssapi" -o "auto" = "$use_gssapi"
 	then
 		use_gssapi=framework
 	fi
@@ -872,7 +872,7 @@ esac
 # for the specification of gssapi and krb5 headers in different locations,
 # which probably ought to be fixed although fixing might raise the issue of
 # trying to build with incompatible versions of gssapi and krb5.
-if test "yes" = "$use_gssapi"
+if test "yes" = "$use_gssapi" -o "auto" = "$use_gssapi"
 then
 	# first, deal with the obvious
 	if test \( -f /usr/include/kerberosv5/krb5.h -o \
@@ -896,8 +896,11 @@ then
 				break
 			fi
 		fi
-		use_gssapi="no"
 	    done
+	    if test "auto" = "$use_gssapi"
+	    then
+		use_gssapi="no"
+	    fi
 	fi
 fi