automation: Avoid changing source files for randconfig tests

We should avoid changing files from the source tree if we don't intend
to commit the result.

We don't really need to check if $EXTRA_FIXED_RANDCONFIG is empty so
add it to the temporary file in all cases.

Signed-off-by: Anthony PERARD <anthony.perard@vates.tech>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

automation/scripts/build

@@ -12,12 +12,12 @@ $cc --version
 # random config or default config
 if [[ "${RANDCONFIG}" == "y" ]]; then
 
-    # Append job-specific fixed configuration
-    if [[ -n "${EXTRA_FIXED_RANDCONFIG}" ]]; then
-        echo "${EXTRA_FIXED_RANDCONFIG}" >> xen/tools/kconfig/allrandom.config
-    fi
+    cp -f xen/tools/kconfig/allrandom.config xen/allrandom.config.tmp
 
-    make -j$(nproc) -C xen KCONFIG_ALLCONFIG=tools/kconfig/allrandom.config randconfig
+    # Append job-specific fixed configuration
+    echo "${EXTRA_FIXED_RANDCONFIG}" >> xen/allrandom.config.tmp
+
+    make -j$(nproc) -C xen KCONFIG_ALLCONFIG=allrandom.config.tmp randconfig
 
     # RANDCONFIG implies HYPERVISOR_ONLY
     HYPERVISOR_ONLY="y"