Remove SkipMountingPartitions from vendor libfstab

SkipMountingPartitions() should only be called from a system process
as the config file is in /system_ext.
Remove it from the vendor variant of libfstab.

Bug: 158301941
Test: build hardware/interfaces/boot/1.1/default/boot_control and check symbol
Change-Id: I834183a623c0711dd79b89486fc3fc80f9710801
diff --git a/fs_mgr/Android.bp b/fs_mgr/Android.bp
index cd64599..ac784b2 100644
--- a/fs_mgr/Android.bp
+++ b/fs_mgr/Android.bp
@@ -149,6 +149,14 @@
         darwin: {
             enabled: false,
         },
+        vendor: {
+            cflags: [
+                // Skipping entries in fstab should only be done in a system
+                // process as the config file is in /system_ext.
+                // Remove the op from the vendor variant.
+                "-DNO_SKIP_MOUNT",
+            ],
+        },
     },
     export_include_dirs: ["include_fstab"],
     header_libs: [