[tests] Suppress unused return value warnings

These cause compile failures due to `-Werror -Wunused-result` when building on NixOS. This PR upstreams patches need to package Swift on that OS.

tests/bsdtests.c

@@ -347,8 +347,8 @@ _test_errno(const char* file, long line, const char* desc, int actual, int expec
 {
 char* actual_str;
 char* expected_str;
-asprintf(&actual_str, "%d\t%s", actual, actual ? strerror(actual) : "");
-asprintf(&expected_str, "%d\t%s", expected, expected ? strerror(expected) : "");
+(void)asprintf(&actual_str, "%d\t%s", actual, actual ? strerror(actual) : "");
+(void)asprintf(&expected_str, "%d\t%s", expected, expected ? strerror(expected) : "");
 _test_print(file, line, desc,
 (actual == expected), "%s", actual_str, "%s", expected_str);
 free(actual_str);
@@ -369,8 +369,8 @@ _test_mach_error(const char* file, long line, const char* desc,
 {
 char* actual_str;
 char* expected_str;
-asprintf(&actual_str, "%d %s", actual, actual ? mach_error_string(actual) : "");
-asprintf(&expected_str, "%d %s", expected, expected ? mach_error_string(expected) : "");
+(void)asprintf(&actual_str, "%d %s", actual, actual ? mach_error_string(actual) : "");
+(void)asprintf(&expected_str, "%d %s", expected, expected ? mach_error_string(expected) : "");
 _test_print(file, line, desc,
 (actual == expected), "%s", actual_str, "%s", expected_str);
 free(actual_str);
@@ -416,12 +416,12 @@ test_cferror(const char *desc, CFErrorRef actual, CFIndex expectedCode)
 if (code != expectedCode) {
 char buffer[BUFSIZ];
 CFStringGetCString(errDesc, buffer, sizeof(buffer), kCFStringEncodingUTF8);
-asprintf(&actual_str, "%ld\t%s", code, buffer);
+(void)asprintf(&actual_str, "%ld\t%s", code, buffer);
 } else {
-asprintf(&actual_str, "%ld", code);
+(void)asprintf(&actual_str, "%ld", code);
 }
 
-asprintf(&expected_str, "%ld", expectedCode);
+(void)asprintf(&expected_str, "%ld", expectedCode);
 _test_print("", (long) 0, desc,
 (code == expectedCode), "%s", actual_str, "%s", expected_str);
 

tests/dispatch_io_muxed.c

@@ -64,7 +64,7 @@ test_file_muxed(void)
 const char *path_separator = "/";
 #endif
 char *path = NULL;
-asprintf(&path, "%s%sdispatchtest_io.XXXXXX", temp_dir, path_separator);
+(void)asprintf(&path, "%s%sdispatchtest_io.XXXXXX", temp_dir, path_separator);
 dispatch_fd_t fd = mkstemp(path);
 if (fd == -1) {
 test_errno("mkstemp", errno, 0);

tests/dispatch_overcommit.c

@@ -48,7 +48,7 @@ main(void)
 int i;
 for (i = 0; i < final; ++i) {
 char* name;
-asprintf(&name, "test.overcommit.%d", i);
+(void)asprintf(&name, "test.overcommit.%d", i);
 
 dispatch_queue_t queue = dispatch_queue_create(name, NULL);
 test_ptr_notnull("dispatch_queue_create", queue);