Disable building libsanitizer in gcc (since musl is used)

[Rielynd]

(Using a version of the book cloned yesterday)
So I noticed that, in the final gcc build run, that the build crashes at libsanitizer due to a few missing includes and missing fields in 'FILE'.
With a bit of digging, I found out that libsanitizer is completely incompatible with musl.
Fix would be appending '--disable-libsanitizer' to the gcc configure options (Ch. 4.9.1)