Feature/G030CxT

[hitech95]

This PR fixes/implements the following bugs/features

• G030CxT variants

The variant G030CxT was missing both default clock and the linker scripts.

Validation

• This has been tested with the validation example as stated in the wiki.
• Tested in Platform.io other than Arduino IDE
• A board with such MCU is running this code since yesterday (so far no locks):

#include <Arduino.h>

#define LED PC7

void setup()
{
  // put your setup code here, to run once:
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED, OUTPUT);
  Serial.begin(115200);
}

void loop()
{
  char hw[] = "Hello World!\0";
  size_t i;
  for (i = 0; i < strlen(hw); i++)
  {
    // put your main code here, to run repeatedly:
    digitalWrite(LED, HIGH); // turn the LED on (HIGH is the voltage level)
    delay(50);               // wait
    digitalWrite(LED, LOW);  // turn the LED off by making the voltage LOW
    delay(50);               // wait
    Serial.print(hw[i]);
  }
  delay(1000); // wait for a second
  Serial.println("...");
}

[ABOSTM]

Except @fpistm ' s remarks, LGTM.

[fpistm]

Hi @hitech95
We do not have a board with this MCU so we cannot test it but as you made some test I will merge it.
Thanks again for your contribution.

Note: in this case I squash all the commits as they are for the same goal add a new board support.

[hitech95]

Ok, got that! Now I know how to contribute for the next time :)