testing/broot: disable on x86

Latest version fails with:

```
note:
/usr/lib/gcc/i586-alpine-linux-musl/9.2.0/../../../../i586-alpine-linux-musl/bin/ld:
/tmp/rustclvHfVF/liblibgit2_sys-c1839c55229d18b6.rlib(refs.o): in function
`git_reference_normalize_name':
refs.c:(.text.git_reference_normalize_name+0xae): undefined reference to
`__stack_chk_fail_local'
```
(and more similar errors)

testing/broot/APKBUILD

@@ -5,7 +5,7 @@ pkgver=0.13.0
 pkgrel=0
 pkgdesc="New way to see and navigate directory trees"
 url="https://github.com/Canop/broot"
-arch="all !s390x"
+arch="all !s390x !x86"
 license="MIT"
 makedepends="cargo"
 source="$pkgname-$pkgver.tar.gz::https://crates.io/api/v1/crates/broot/$pkgver/download"