Add CHANGELOG entry for #959

Add a CHANGELOG entry for pull request #959, which fixed the
CARGO_CFG_TARGET_ARCH environment variable query from a build script in
a cross-compilation context.

Signed-off-by: Daniel Müller <[email protected]>

Author: d-e-s-o

libbpf-cargo/CHANGELOG.md

@@ -1,3 +1,9 @@
+Unreleased
+----------
+- Fixed incorrect Cargo environment variable query when used in build
+  script context
+
+
 0.24.4
 ------
 - Adjusted skeleton generation code to work around `libbpf` forward