patch 8.0.1717: C89 check causes too much trouble

Problem:    C89 check causes too much trouble.
Solution:   Remove enforcing C89 for now.
diff --git a/src/auto/configure b/src/auto/configure
index 29dadf2..fc7bb5a 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -4206,8 +4206,6 @@
       CFLAGS="$CFLAGS -fno-strength-reduce"
     fi
   fi
-
-    CPPFLAGS="$CPPFLAGS -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700"
 fi
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for clang version" >&5
@@ -14434,10 +14432,6 @@
 	CFLAGS="-D_ALL_SOURCE -Wc,float\(ieee\),dll"
 fi
 
-if test "$GCC" = yes -a "$GUITYPE" != "GTK" -a "X$RUBY_CFLAGS" = "X"; then
-  CFLAGS="$CFLAGS -ansi"
-fi
-
 ac_config_files="$ac_config_files auto/config.mk:config.mk.in"
 
 cat >confcache <<\_ACEOF
diff --git a/src/configure.ac b/src/configure.ac
index eef443b..ff0c726 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -61,9 +61,6 @@
       CFLAGS="$CFLAGS -fno-strength-reduce"
     fi
   fi
-
-  dnl Declare what standards the code should comply with
-  CPPFLAGS="$CPPFLAGS -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700"
 fi
 
 dnl clang-500.2.75 or around has abandoned -f[no-]strength-reduce and issues a
@@ -4403,13 +4400,6 @@
 	CFLAGS="-D_ALL_SOURCE -Wc,float\(ieee\),dll"
 fi
 
-dnl Declare what standards the code should comply with.
-dnl But not when using GTK, the header files cause all kinds of warnings.
-dnl But not when using Ruby, it needs "inline".
-if test "$GCC" = yes -a "$GUITYPE" != "GTK" -a "X$RUBY_CFLAGS" = "X"; then
-  CFLAGS="$CFLAGS -ansi"
-fi
-
 dnl write output files
 AC_OUTPUT(auto/config.mk:config.mk.in)
 
diff --git a/src/version.c b/src/version.c
index 1c6c15d..207048f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1717,
+/**/
     1716,
 /**/
     1715,