Restore a change in the documentation.
Using the wildcard name MBEDTLS_PLATFORM_XXX_ALT made the Travis build
fail.
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index c9332e1..a617d06 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -131,7 +131,7 @@
//#define MBEDTLS_PLATFORM_NO_STD_FUNCTIONS
/**
- * \def MBEDTLS_PLATFORM_XXX_ALT
+ * \def MBEDTLS_PLATFORM_EXIT_ALT
*
* MBEDTLS_PLATFORM_XXX_ALT: Uncomment a macro to let mbed TLS support the
* function in the platform abstraction layer.