Update php version number to 3.7.0RC2 (#5666)

* Update php version number to 3.7.0RC2

* Update version number in source code

php/ext/google/protobuf/package.xml

@@ -10,10 +10,10 @@
   <email>protobuf-opensource@google.com</email>
   <active>yes</active>
  </lead>
- <date>2019-01-24</date>
+ <date>2019-02-01</date>
  <time>10:22:43</time>
  <version>
-  <release>3.7.0</release>
+  <release>3.7.0RC2</release>
   <api>3.7.0</api>
  </version>
  <stability>
@@ -264,14 +264,14 @@ G  A release.
   </release>
   <release>
    <version>
-    <release>3.7.0rc2</release>
-    <api>3.7.0rc2</api>
+    <release>3.7.0RC2</release>
+    <api>3.7.0</api>
    </version>
    <stability>
     <release>stable</release>
     <api>stable</api>
    </stability>
-   <date>2019-01-24</date>
+   <date>2019-02-1</date>
    <time>10:22:43</time>
    <license uri="https://opensource.org/licenses/BSD-3-Clause">3-Clause BSD License</license>
    <notes>GA release.</notes>

php/ext/google/protobuf/protobuf.h

@@ -37,7 +37,7 @@
 #include "upb.h"
 
 #define PHP_PROTOBUF_EXTNAME "protobuf"
-#define PHP_PROTOBUF_VERSION "3.6.1"
+#define PHP_PROTOBUF_VERSION "3.7.0RC2"
 
 #define MAX_LENGTH_OF_INT64 20
 #define SIZEOF_INT64 8