Fix some potential problems detected by clang.

Most of these are unnecessary comparisons and functions returning the
wrong types.

arogue5/mdport.c

@@ -132,7 +132,7 @@ md_hasclreol(void)
 
 static int md_standout_mode = 0;
 
-int
+void
 md_raw_standout(void)
 {
 #ifdef _WIN32
@@ -155,7 +155,7 @@ md_raw_standout(void)
 #endif
 }
 
-int
+void
 md_raw_standend(void)
 {
 #ifdef _WIN32
@@ -223,7 +223,7 @@ md_fdopen(int fd, char *mode)
 #endif
 }
 
-int
+void
 md_normaluser(void)
 {
 #ifndef _WIN32
@@ -596,7 +596,7 @@ md_rand(void)
 #endif
 }
 
-int
+void
 md_srand(int seed)
 {
 #ifdef _WIN32