sulong: CHANGELOG entry about lazy libsulong++

sulong/CHANGELOG.md

@@ -2,6 +2,18 @@
 
 Changes:
 
+* C++ support (libsulong++) is no longer loaded by default. Instead, it is
+  enabled if `libc++abi` is loaded. Executables (ELF, Mach-O) compiled with
+  the toolchain usually have a dependency on this library and will continue
+  to work.  Plain bitcode files, which do not allow to specify dependencies,
+  may fail with an error similar to the following:
+  ```
+  Global variable _ZNSt3__15ctypeIcE2idE is declared but not defined.
+  ```
+  This can be solved by either compiling it into a proper executable, or by
+  specifying the depdendency on the command line (e.g., `lli --lib libc++.so.1 ...`
+  on Linux or `lib --lib libc++.1.dylib` on macOS).
+
 * Module initialization order is now only based on the dependencies recorded in the
   ELF/Mach-O file instead of looking at imported symbols. Consequently, the order
   plain bitcode files are initialized might change since they do not allow recording