Segfault at if '\<letter>' entered inside string & if compiled with musl-gcc (a proposed fix is also included)

if kilo is compiled with the musl gcc wrapper, the following will trigger a segfault

`> kilo new_file.c`

then enter on first line:

`puts("\e`

This will trigger a segfault in musl (but not glibc)

The following will fix the problem - change line 445 from:

`if (*p == '\\') {`

To:

`if (*p == '\\' && *(p+1)) {`