patch 8.0.1717: C89 check causes too much trouble

Problem:    C89 check causes too much trouble.
Solution:   Remove enforcing C89 for now.

src/auto/configure

@@ -4206,8 +4206,6 @@ if test "$GCC" = yes; then
      CFLAGS="$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 @@ if test "$zOSUnix" = "yes"; then
	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

src/configure.ac

@@ -61,9 +61,6 @@ if test "$GCC" = yes; then
      CFLAGS="$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 @@ if test "$zOSUnix" = "yes"; then
	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)

src/version.c

@@ -762,6 +762,8 @@ static char *(features[]) =

static int included_patches[] =
{   /* Add new patch number below this line */
/**/
    1717,
/**/
    1716,
/**/