Drupal: PHP7 fixes for boinc modules

[drshawnkwang]

Description of the Change
Modified boinc modules to fix PHP 7 compatibility issues

• mysql_xyz() functions replaced with mysqli_mxyz() functions.
• Removed references to ini settings safe_mode.
• Updated a class constructor to use modern PHP standards.

Release Notes
N/A

Part of https://dev.gridrepublic.org/browse/DBOINCP-468

[drshawnkwang]

Closing - this needs to be tested further - will reopen/resubmit later.

[drshawnkwang]

Did some more testing: Scrutinizer reports bugs on the new mysqli_num_rows() functions:

$variable of type `false|resource` is incompatible with the type `mysqli_result` expected by parameter `$result` of `mysqli_num_rows()`. ( Ignorable by Annotation )

I tested the code and dumped out the class type of variable with get_class(), and it is an object of class mysqli_result. I don't know why the Scrutinizer flags the variable as being something else. I believe that the code should work. db_query will return a mysqli_result which will be passed to mysqli_num_rows() and be processed correctly.

As a result I am re-opening this PR.

[ChristianBeer]

I also noticed a false positive involving incompatible types. I opened a bug report with scrutinizer about that. You could probably for now ignore those kind of bugs (while still doing a quick check though).