Fix some potential problems detected by clang.

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

arogue7/mdport.c

@@ -111,7 +111,7 @@ md_init(void)
 
 static int md_standout_mode = 0;
 
-int
+void
 md_raw_standout(void)
 {
 #ifdef _WIN32
@@ -134,7 +134,7 @@ md_raw_standout(void)
 #endif
 }
 
-int
+void
 md_raw_standend(void)
 {
 #ifdef _WIN32
@@ -213,7 +213,7 @@ md_creat(char *file, int mode)
 }
 
 
-int
+void
 md_normaluser(void)
 {
 #ifndef _WIN32
@@ -581,7 +581,7 @@ md_rand(void)
 #endif
 }
 
-int
+void
 md_srand(int seed)
 {
 #ifdef _WIN32