Symbian Support

Changes
------------
Symbian doesn't have 'HZ' defined in sys/param.h. Use 1 instead.
Symbian doesn't have linux headers.
Symbian doesn't have fsStat. Let's hack around that for now. 32MB free space, 128MB total space. This will never hit anyway.
Protected namespace with __cplusplus.

Confirmed working on Nokia N8 (VideoCore III) and Nokia 808 (VideoCore IV).

There is no vchiq on Symbian. Uses its own messaging system.

How to
----------
To test on Symbian with an existing Qt project
Add the following to your project.pro file:
```
BCM_HEADERS = C:/Users/Me/Desktop/videocore/userland
INCLUDEPATH += $${BCM_HEADERS}/ \
    $${BCM_HEADERS}/interface/vchi/ \
    $${BCM_HEADERS}/interface/vcos/pthreads/
LIBS += -lvcos -lvchi -lvcstreamio
DEFINES += USE_VCHIQ_ARM
```
where BCM_HEADERS is where you have cloned this git.

Add the following to your main.cpp file:
```C++
#include "vchi.h"
int main() {
...
    vcos_init();
...
}
```