patch 9.0.0491: no good reason to build without the float feature

Problem:    No good reason to build without the float feature.
Solution:   Remove configure check for float and "#ifdef FEAT_FLOAT".
diff --git a/src/gui_x11.c b/src/gui_x11.c
index 7293ac4..fa81875 100644
--- a/src/gui_x11.c
+++ b/src/gui_x11.c
@@ -1184,7 +1184,7 @@
 		cmdline_options, XtNumber(cmdline_options),
 		CARDINAL &gui_argc, gui_argv);
 
-# if defined(FEAT_FLOAT) && defined(LC_NUMERIC)
+# if defined(LC_NUMERIC)
     {
 	// The call to XtOpenDisplay() may have set the locale from the
 	// environment. Set LC_NUMERIC to "C" to make sure that strtod() uses a