Add ChangeLog for c_build_helper improvements

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/ChangeLog.d/c-build-helper-hostcc.txt b/ChangeLog.d/c-build-helper-hostcc.txt
new file mode 100644
index 0000000..ebf77b3
--- /dev/null
+++ b/ChangeLog.d/c-build-helper-hostcc.txt
@@ -0,0 +1,4 @@
+Features
+   * Use HOSTCC (if it is set) when compiling C code during generation of the
+     generated files. This allows them to be generated when CC is set for
+     cross compilation.