fs_mgr: mount: don't set the block device as ro for recovery

* In recovery we need to be able to edit the block device
   after it's been mounted.
   This allows, for example, to wipe system after mounting it

Change-Id: Ie536d275643e9d6063bba789e4cd2fa2671fc8fa

fs_mgr/Android.bp

@@ -159,6 +159,11 @@ cc_library {
     srcs: [
         ":libfiemap_passthrough_srcs",
     ],
+    target: {
+        recovery: {
+            cflags: ["-DSKIP_SET_BLK_RO"],
+        },
+    },
 }
 
 cc_library {

fs_mgr/fs_mgr.cpp

@@ -880,9 +880,11 @@ static int __mount(const std::string& source, const std::string& target, const F
     }
     PINFO << __FUNCTION__ << "(source=" << source << source_missing << ",target=" << target
           << target_missing << ",type=" << entry.fs_type << ")=" << ret;
+#ifndef SKIP_SET_BLK_RO
     if ((ret == 0) && (mountflags & MS_RDONLY) != 0) {
         fs_mgr_set_blk_ro(source);
     }
+#endif
     if (ret == 0) {
         android::base::SetProperty("ro.boottime.init.mount." + Basename(target),
                                    std::to_string(t.duration().count()));