Add check for nice priority changing

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@1925

configure.in

@@ -187,6 +187,16 @@ else
   AC_MSG_WARN([Can't find libSDL_sound, libSDL_sound support disabled])
 fi
 
+AH_TEMPLATE(C_PRIORITY_NICE,[Define to 1 if you have nice priority changing support])
+AC_MSG_CHECKING(for nice priority changing)
+AC_LINK_IFELSE([
+#include <sys/resource.h>
+int main(int argc,char * argv[]) {
+	return nice(10);
+};
+],AC_MSG_RESULT(yes);AC_DEFINE(C_PRIORITY_NICE,1),AC_MSG_RESULT(no))
+
+
 dnl Some host detection and actions for them
 case "$target" in
     *-*-cygwin* | *-*-mingw32*)