[OpenMP] Avoid warnings about unused static functions on windows

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.

Differential Revision: https://reviews.llvm.org/D96584

openmp/runtime/src/kmp_environment.cpp

@@ -376,6 +376,7 @@ static void ___kmp_env_blk_parse_windows(
         { "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.
@@ -423,6 +424,7 @@ ___kmp_env_blk_parse_unix(kmp_env_blk_t *block, // M: Env block to fill.
   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.

openmp/runtime/src/kmp_io.cpp

@@ -84,6 +84,7 @@ void __kmp_close_console(void) {
 static void __kmp_redirect_output(void) {
   __kmp_acquire_bootstrap_lock(&__kmp_console_lock);
 
+  (void)is_console;
   if (!__kmp_console_exists) {
     HANDLE ho;
     HANDLE he;