Updated CHANGES.txt and PHP release notes for 3.15.5

CHANGES.txt

@@ -1,3 +1,14 @@
+2021-03-04 version 3.15.5 (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
+
+  Ruby
+  * Fixed quadratic memory use in array append (#8379)
+
+  PHP
+  * Fixed quadratic memory use in array append (#8379)
+
+  C++
+  * Do not disable RTTI by default in the CMake build (#8377)
+
 2021-03-02 version 3.15.4 (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
 
   Ruby

php/ext/google/protobuf/package.xml

@@ -22,8 +22,8 @@
  </stability>
  <license uri="https://opensource.org/licenses/BSD-3-Clause">3-Clause BSD License</license>
  <notes>
- New changes in 3.15.4:
- * read_property() handler is not supposed to return NULL (#8362)
+ New changes in 3.15.5:
+ * Fixed quadratic memory use in array append (#8379)
  </notes>
  <contents>
   <dir baseinstalldir="/" name="/">