[OpenMP] Avoid warnings about unused static functions on windows

[mstorsjo]

Summary

Add ifdefs around one function that only is used in unix build configurations.

Add a void cast for a windows specific function that currently is unused but may be intended to be used at some point.

[AndreyChurbanov]

LGTM

openmp/runtime/src/kmp_environment.cpp

 #endif
 
 /* Unix environment block is a array of pointers to variables, last pointer in
    array is NULL:
 
         { "HOME=/home/lev", "TERM=xterm", NULL }
 */
 
+#if KMP_OS_UNIX
 static void
 ___kmp_env_blk_parse_unix(kmp_env_blk_t *block, // M: Env block to fill.
                           char **env // I: Unix environment to parse.
                           ) {
   char *bulk = NULL;
   kmp_env_var_t *vars = NULL;
   int count = 0;
   size_t size = 0; // Size of bulk.
// Loop thru all the vars.
     }
   }
 
   // Fill out result.
   block->bulk = bulk;
   block->vars = vars;
   block->count = count;
 }
+#endif
 
 void __kmp_env_blk_init(kmp_env_blk_t *block, // M: Block to initialize.
                         char const *bulk // I: Initialization string, or NULL.
                         ) {
 
   if (bulk != NULL) {
     ___kmp_env_blk_parse_string(block, bulk);
   } else {

openmp/runtime/src/kmp_io.cpp

void __kmp_close_console(void) {
   }
 }
 
 /* For windows, call this before stdout, stderr, or stdin are used.
    It opens a console window and starts processing */
 static void __kmp_redirect_output(void) {
   __kmp_acquire_bootstrap_lock(&__kmp_console_lock);
 
+  (void)is_console;
   if (!__kmp_console_exists) {
     HANDLE ho;
     HANDLE he;
 
     __kmp_str_buf_init(&__kmp_console_buf);
 
     AllocConsole();
     // We do not check the result of AllocConsole because