Replace fbsource// with // in xplat/js/ files [1]

Summary:
`fbsource//xplat` and `//xplat` are equivalent for FB BUCK targets. Removing extra prefix for consistency.

Changelog: [Internal]

Reviewed By: scottrice

Differential Revision: D20495655

fbshipit-source-id: a57b72f694c533e2e16dffe74eccb8fdec1f55f5

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/BUCK

@@ -32,11 +32,11 @@ rn_xplat_cxx_library(
         react_native_xplat_target("fabric/components/scrollview:scrollview"),
         react_native_xplat_target("utils:utils"),
         react_native_target("jni/react/jni:jni"),
-        "fbsource//xplat/fbsystrace:fbsystrace",
-        "fbsource//xplat/folly:molly",
-        "fbsource//xplat/jsi:JSIDynamic",
-        "fbsource//xplat/jsi:jsi",
-        "fbsource//xplat/third-party/linker_lib:atomic",
+        "//xplat/fbsystrace:fbsystrace",
+        "//xplat/folly:molly",
+        "//xplat/jsi:JSIDynamic",
+        "//xplat/jsi:jsi",
+        "//xplat/third-party/linker_lib:atomic",
         FBJNI_TARGET,
     ],
 )

ReactAndroid/src/main/java/com/facebook/react/jscexecutor/BUCK

@@ -26,7 +26,7 @@ rn_xplat_cxx_library(
         react_native_target("java/com/facebook/react/jscexecutor:jscexecutor"),
     ],
     deps = [
-        "fbsource//xplat/folly:molly",
+        "//xplat/folly:molly",
         FBJNI_TARGET,
         react_native_target("jni/react/jni:jni"),
         react_native_xplat_target("jsi:JSCRuntime"),

ReactAndroid/src/main/java/com/facebook/react/turbomodule/core/jni/BUCK

@@ -31,8 +31,8 @@ rn_xplat_cxx_library(
         FBJNI_TARGET,
     ],
     exported_deps = [
-        "fbsource//xplat/jsi:jsi",
         ":callinvokerholder",
+        "//xplat/jsi:jsi",
         react_native_xplat_target("turbomodule/core:core"),
     ],
 )