Fix macroization of inline in C++

When compiling as C++, MSVC complains about our macroization of a keyword.
Stop doing that as we know inline is always available in C++
diff --git a/ChangeLog b/ChangeLog
index 5a8f63c..8dac7a4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,7 @@
 Bugfix
    * Fix compile error in net.c with musl libc. Found and patch provided by
      zhasha (#278).
+   * Fix macroization of 'inline' keywork when building as C++. (#279)
 
 = mbed TLS 1.3.13 released 2015-09-17