Provide placeholder OEMCrypto file for RISCV

In order to build RISCV targets in internal master, a value must be
supplied to libwvdrmengine to satisfy the build for riscv64. For now,
point the build to the x86_64 file as a workaround.

Change-Id: I632198279586f2ab974aed9daadd72f378e13094

libwvdrmengine/level3/Android.bp

@@ -71,6 +71,13 @@ cc_library_static {
                 "x86_64/libl3oemcrypto.cpp",
             ],
         },
+        riscv64: {
+            srcs: [
+                // Until the L3 OEMCrypto files are regenerated for riscv64
+                // platforms, point to x86_64 to satisfy the builder.
+                "x86_64/libl3oemcrypto.cpp",
+            ],
+        },
     },
     proprietary: true,