Raise libv8 required version to 6.0.4 [skip ci]

Author: pinepain

README.md

@@ -73,7 +73,7 @@ in your IDE and other code-analysis tools.
 ### Requirements
 
 #### V8
-You will need a recent v8 Google JavaScript engine version installed. At this time the extension is tested on 5.9.5.
+You will need a recent v8 Google JavaScript engine version installed. At this time the extension is tested on 6.0.4.
 
 #### PHP
 This extension is PHP7-only. It works and tested with both PHP 7.0 and PHP 7.1.
@@ -96,7 +96,7 @@ $ php --ri v8
 
 While [pinepain/php](https://launchpad.net/~pinepain/+archive/ubuntu/php) PPA targets to contain all necessary
 extensions with dependencies, you may find
-[pinepain/libv8-5.9](https://launchpad.net/~pinepain/+archive/ubuntu/libv8-5.9),
+[pinepain/libv8-6.0](https://launchpad.net/~pinepain/+archive/ubuntu/libv8-6.0),
 [pinepain/libv8-experimental](https://launchpad.net/~pinepain/+archive/ubuntu/libv8-experimental) and
 [pinepain/php-v8](https://launchpad.net/~pinepain/+archive/ubuntu/php-v8) standalone PPAs useful.
 
@@ -108,7 +108,7 @@ $ brew tap homebrew/dupes
 $ brew tap homebrew/php
 $ brew tap pinepain/devtools
 $ brew install php70 
-$ brew install v8@5.9
+$ brew install v8@6.0
 $ brew install php70-v8
 $ php --ri v8
 ```

config.m4

@@ -8,7 +8,7 @@ if test "$PHP_V8" != "no"; then
   SEARCH_PATH="/usr/local /usr"
   SEARCH_FOR="include/v8.h"
 
-  V8_MIN_API_VERSION_STR=5.9.5
+  V8_MIN_API_VERSION_STR=6.0.4
 
   DESIRED_V8_VERSION=`echo "${V8_MIN_API_VERSION_STR}" | $AWK 'BEGIN { FS = "."; } { printf "%s.%s", [$]1, [$]2;}'`