Define try_chdir everywhere

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/host_test.function b/tests/suites/host_test.function
index 736883f..d8ff49e 100644
--- a/tests/suites/host_test.function
+++ b/tests/suites/host_test.function
@@ -442,7 +442,7 @@
  *
  * Failures are silent.
  */
-static void try_chdir(const char *argv0)
+static void try_chdir_if_supported(const char *argv0)
 {
     /* We might want to allow backslash as well, for Windows. But then we also
      * need to consider chdir() vs _chdir(), and different conventions
@@ -467,6 +467,13 @@
     }
     mbedtls_free(path);
 }
+#else /* MBEDTLS_HAVE_CHDIR */
+/* No chdir() or no support for parsing argv[0] on this platform. */
+static void try_chdir_if_supported(const char *argv0)
+{
+    (void) argv0;
+    return;
+}
 #endif /* MBEDTLS_HAVE_CHDIR */
 
 /**
diff --git a/tests/suites/main_test.function b/tests/suites/main_test.function
index eb74e8f..6ab4a56 100644
--- a/tests/suites/main_test.function
+++ b/tests/suites/main_test.function
@@ -237,7 +237,6 @@
 #endif
 #endif
 
-#ifdef MBEDTLS_HAVE_CHDIR
     /* Try changing to the directory containing the executable, if
      * using the default data file. This allows running the executable
      * from another directory (e.g. the project root) and still access
@@ -249,8 +248,7 @@
      * test-specific files such as the outcome file, which is arguably
      * not desirable and should be fixed later.
      */
-    try_chdir(argv[0]);
-#endif /* MBEDTLS_HAVE_CHDIR */
+    try_chdir_if_supported(argv[0]);
 
     int ret = mbedtls_test_platform_setup();
     if (ret != 0) {