fixes to make it suitable for compiling on hardened systems

[alsotoes]

• Avoid calling gcc or g++ directly, crash the compilation on several hardened systems
• Change external verbose variable on error.h, crash the compilation process for redeclaration on several objects compilation
• Dropping Werror compilation flag as is making the compilation fail on warnings this project is not intended to fix

Signed-off-by: alsotoes [email protected]