Include capi 1.5.1 changelog (#5126)

Changelog from #5123

CHANGELOG.md

@@ -2,13 +2,16 @@
 
 ## icu4x 1.5.x
 
+
 - `icu_calendar`
   - (1.5.1) Fix Japanese calendar Gregorian era year 0 (https://github.com/unicode-org/icu4x/issues/4968)
   - (1.5.2) Enforce C,packed, not just packed, on ULE types, fixing for incoming changes to `repr(Rust)` (https://github.com/unicode-org/icu4x/pull/5049)
 - `icu_datetime`
   - (1.5.1) Fix incorrect assertion in week-of-year formatting (https://github.com/unicode-org/icu4x/issues/4977)
 - `icu_casemap`
   - (1.5.1) Enforce C,packed, not just packed, on ULE types, fixing for incoming changes to `repr(Rust)` (https://github.com/unicode-org/icu4x/pull/5049)
+- `icu_capi`
+  - (1.5.1) Fix situations in which `libc_alloc` is specified as a dependency (https://github.com/unicode-org/icu4x/pull/5119)
 - `icu_properties`
   - (1.5.1) Enforce C,packed, not just packed, on ULE types, fixing for incoming changes to `repr(Rust)` (https://github.com/unicode-org/icu4x/pull/5049)
 - `zerovec`