More GCC compatibility/warning fixes (#3118)

* Wrap >4-char literals in a MULTI_CHAR macro

Modern compilers do not support CW's non-standard behavior with
>4 char literals. We can, however, use a constexpr function to
compute the u64 values directly. This leaves <=4 char literals
unchanged.

* Replace non-pointer usages of NULL with 0

* Define NULL to nullptr on C++11 and above

* Fix more -Wpointer-arith and -Woverflow warnings

* Replace u32/s32 with uintptr_t/intptr_t where appropriate

* JSUOutputStream: Overload all standard int types

1 files changed, 7 insertions, 7 deletions

diff --git a/src/d/d_file_sel_warning.cpp b/src/d/d_file_sel_warning.cpp
index 3063012ea0..4fbce3920b 100644
--- a/src/d/d_file_sel_warning.cpp
+++ b/src/d/d_file_sel_warning.cpp
@@ -59,20 +59,20 @@ void dFile_warning_c::screenSet() {
     mFileWarn.Scr->animation();
 
     mFileWarn.mFont = mDoExt_getMesgFont();
-    mpRootPane = new CPaneMgr(mFileWarn.Scr, 'Nm_02', 0, NULL);
+    mpRootPane = new CPaneMgr(mFileWarn.Scr, MULTI_CHAR('Nm_02'), 0, NULL);
     JUT_ASSERT(0, mpRootPane != NULL);
     field_0x34 = mpRootPane->getTranslateY();
 
 #if REGION_JPN
-    mFileWarn.Scr->search('ms_for_2')->hide();
-    mFileWarn.Scr->search('ms_for_3')->hide();
+    mFileWarn.Scr->search(MULTI_CHAR('ms_for_2'))->hide();
+    mFileWarn.Scr->search(MULTI_CHAR('ms_for_3'))->hide();
 
-    field_0x20 = static_cast<J2DTextBox*>(mFileWarn.Scr->search('w_msg_jp'));
+    field_0x20 = static_cast<J2DTextBox*>(mFileWarn.Scr->search(MULTI_CHAR('w_msg_jp')));
 #else
-    mFileWarn.Scr->search('w_msg_jp')->hide();
-    mFileWarn.Scr->search('ms_for_2')->hide();
+    mFileWarn.Scr->search(MULTI_CHAR('w_msg_jp'))->hide();
+    mFileWarn.Scr->search(MULTI_CHAR('ms_for_2'))->hide();
 
-    field_0x20 = static_cast<J2DTextBox*>(mFileWarn.Scr->search('ms_for_3'));
+    field_0x20 = static_cast<J2DTextBox*>(mFileWarn.Scr->search(MULTI_CHAR('ms_for_3')));
 #endif
     field_0x20->show();
     field_0x20->setFont(mFileWarn.mFont);