Fixes exception in ToString()

[josesimoes]

Description

Implements hal_snprintf for ChibiOS nanoCRT allowing printf .

Motivation and Context

• Fixes/Closes/Resolves ToString() throws exception Home#215
• Fixes/Closes/Resolves Exception with "N0" format string and integer value of 0 Home#118

How Has This Been Tested? (if applicable)

• C# test app with a call to Int32.ToString() and Int32.ToString("N0") without throwing any exception.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Signed-off-by: José Simões jose.simoes@eclo.solutions

[nfbot]

Hi @josesimoes,

I'm nanoFramework bot.
Thank you for your contribution!

A human will be reviewing it shortly. 😉