Replace malloc.h by stdlib.h

On true unices malloc.h was never available and on Linux one should
include stdlib.h instead. While this change is necessary to build
rbdoom3 on FreeBSD and other true unices, the big question is what
it means to Windows.

neo/amplitude/amplitude.cpp

@@ -27,7 +27,6 @@ If you have questions concerning this license or the applicable additional terms
 */
 
 #include <stdio.h>
-#include <malloc.h>
 #include <string.h>
 #include <math.h>
 #include <stdlib.h>

neo/idlib/Heap.cpp

@@ -36,7 +36,7 @@ If you have questions concerning this license or the applicable additional terms
 //	memory allocation all in one place
 //
 //===============================================================
-#include <malloc.h>
+#include <stdlib.h>
 #undef new
 
 /*

neo/idlib/ParallelJobList_JobHeaders.h

@@ -51,14 +51,14 @@ If you have questions concerning this license or the applicable additional terms
 // RB begin
 #if defined(__MINGW32__)
 //#include <sal.h> 	// RB: missing __analysis_assume
+#include <malloc.h> // DG: _alloca16 needs that
 
 #ifndef __analysis_assume
 #define __analysis_assume( x )
 #endif
 
-#include <malloc.h> // DG: _alloca16 needs that
-
 #elif defined(__linux__)
+#include <malloc.h> // DG: _alloca16 needs that
 #include <signal.h>
 #endif
 // RB end

neo/idlib/sys/sys_includes.h

@@ -117,7 +117,7 @@ If you have questions concerning this license or the applicable additional terms
 #endif // #if defined(_WIN32)
 // RB end
 
-#include <malloc.h>							// no malloc.h on mac or unix
+#include <stdlib.h>							// no malloc.h on mac or unix
 #undef FindText								// fix namespace pollution