automation: enable rombios build on Alpine

It's now safe to enable the build of rombios on Alpine systems, as
hvmloader already builds fine there.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Wei Liu <wl@xen.org>
Release-Acked-by: Ian Jackson <iwj@xenproject.org>

automation/scripts/build

@@ -31,9 +31,8 @@ fi
 if ! test -z "$(ldd /bin/ls|grep musl|head -1)"; then
     # disable --disable-werror for QEMUU when building with MUSL
     cfgargs+=("--with-extra-qemuu-configure-args=\"--disable-werror\"")
-    # hvmloader doesn't build on MUSL systems
-    cfgargs+=("--disable-seabios")
-    cfgargs+=("--disable-rombios")
+    # SeaBIOS doesn't build on MUSL systems
+    cfgargs+=("--with-system-seabios=/bin/false")
 fi
 
 # Qemu requires Python 3.5 or later