Change default value inside struct dyn

[ghost]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've added tests that prove my fix is effective or that my feature works (if possible)
• I've updated the documentation and the radare2 book with the relevant information (if needed)

Detailed description
The error value (not found) inside RBinElfDynamicInfo was 0. The problem is that some value inside the dynamic section are 0 and it is VALID. So i change the default value.

PS: All size have a value of 0, imho an invalid size is 0 not a big value.

Test plan

...

Closing issues
#12732

[ghost]

@ret2libc Any opinion on this?

[ret2libc]

LGTM

[ghost]

@ret2libc the appveyor has ended but you can't see it if you don't click on the link

[ret2libc]

@ret2libc the appveyor has ended but you can't see it if you don't click on the link

I see... probably some issues with Github. Let's wait and see if it pass in a short time, otherwise @XVilka or @radare can merge it anyway.

[radare]

stil WIP? lgtm

[ghost]

Nope @radare i forget to remove the flag

[ret2libc]

I restarted appveyor build which was stuck.