[reclient] Add target_os=fuchsia support

Modify rbe.gni to use rewrapper_linux.cfg as reclient config file
if target_os is set to fuchsia

Bug: 1288593
Change-Id: Ic146e6a12f6f13cf6eb3e1477122d25cda3e1da3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3413014
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Bozydar Szadkowski <bozydar@google.com>
Cr-Commit-Position: refs/heads/main@{#962717}

build/toolchain/rbe.gni

@@ -33,7 +33,7 @@ if (!use_remoteexec && use_rbe) {
 }
 
 # Configuration file selection based on operating system.
-if (is_linux || is_android || is_chromeos) {
+if (is_linux || is_android || is_chromeos || is_fuchsia) {
   rbe_cc_cfg_file = "${rbe_cfg_dir}/chromium-browser-clang/rewrapper_linux.cfg"
 }
 if (is_win) {