Remove the -no-rtti option from configure

It only applied to Windows (not MSVC, like the help said) and the build
was broken with this option. So remove it, as we clearly never test
this.

[ChangeLog][Windows] The -no-rtti configure option was removed, as Qt
5.8 fails to build under that condition. To disable RTTI on user code,
add to your .pro file: CONFIG += rtti_off.

Change-Id: I2bc52f3c7a574209b213fffd149aae1b8d0cf9df
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

config_help.txt

@@ -99,7 +99,6 @@ Build options:
 
   -c++std <edition> .... Select C++ standard <edition> [c++1z/c++14/c++11]
                          (Not supported with MSVC)
-  -rtti ................ Build with Runtime Type Information [yes] (MSVC only)
 
   -sse2 ................ Use SSE2 instructions [auto]
   -sse3/-ssse3/-sse4.1/-sse4.2/-avx/-avx2/-avx512

configure.json

@@ -107,7 +107,6 @@
             "reduce-relocations": { "type": "boolean", "name": "reduce_relocations" },
             "release": { "type": "enum", "name": "debug", "values": { "yes": "no", "no": "yes" } },
             "rpath": "boolean",
-            "rtti": "boolean",
             "sanitize": "sanitize",
             "sdk": "string",
             "separate-debug-info": { "type": "boolean", "name": "separate_debug_info" },
@@ -554,12 +553,6 @@
             "autoDetect": false,
             "output": [ { "type": "varAppend", "name": "EXTRA_RPATHS", "value": "input.rpaths" } ]
         },
-        "rtti": {
-            "label": "Build with RTTI",
-            "comment": "mkspecs/features/win32/default_pre.prf sets no-rtti. Follow default behavior of configure.exe by overriding with rtti.",
-            "condition": "config.win32",
-            "output": [ "publicConfig" ]
-        },
         "force_asserts": {
             "label": "Force assertions",
             "autoDetect": false,

mkspecs/features/win32/default_pre.prf

-CONFIG = rtti_off incremental_off windows $$CONFIG
+CONFIG = incremental_off windows $$CONFIG
 load(default_pre)