Turn assert functionality standard-conforming in jerry-libc

Introducing the `assert.h` public header with the `assert(x)` macro
and already making use of it in jerry-libc sources. These newly
introduced ISO C-conforming features replace the non-conforming
`LIBC_ASSERT` and `LIBC_NDEBUG` at no cost, and they also have the
benefit that we can expose `assert` in a public header and make it
useful to jerry-libc users.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

jerry-libc/CMakeLists.txt

@@ -1,4 +1,4 @@
-# Copyright 2015 Samsung Electronics Co., Ltd.
+# Copyright 2015-2016 Samsung Electronics Co., Ltd.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -25,7 +25,7 @@ set(COMPILE_FLAGS_LIBC "${COMPILE_FLAGS_JERRY} ${C_FLAGS_JERRY}")
    set(DEFINES_LIBC_DEBUG )
 
   # Release
-   set(DEFINES_LIBC_RELEASE LIBC_NDEBUG)
+   set(DEFINES_LIBC_RELEASE NDEBUG)
 
 # Architecture-specific
   # x86_64