Fix google-build-using-namespace warnings in cpu_ref.

* Remove "using namespace ..." statements.
* Replace them with using declarations of the required names.
* Enclose the C++ methods and static and extern "C" functions with
  namespace android and renderscript.
* Keep global C++ functions as-is and add using declarations for them.

Bug: 32670901
Test: build with WITH_TIDY=1
Change-Id: I818de466e8786a6c4f9ce0cd8e0fe027f34d7fad
diff --git a/cpu_ref/rsCpuIntrinsicBLAS.cpp b/cpu_ref/rsCpuIntrinsicBLAS.cpp
index 9b0a8ed..2a5ab21 100644
--- a/cpu_ref/rsCpuIntrinsicBLAS.cpp
+++ b/cpu_ref/rsCpuIntrinsicBLAS.cpp
@@ -20,9 +20,6 @@
 #include "rsCpuBLASDispatch.h"
 #include "eight_bit_int_gemm.h"
 
-using namespace android;
-using namespace android::renderscript;
-
 namespace android {
 namespace renderscript {
 
@@ -60,9 +57,6 @@
 
 };
 
-}
-}
-
 void RsdCpuScriptIntrinsicBLAS::populateScript(Script *s) {
     s->mHal.info.exportedVariableCount = 0;
 }
@@ -739,12 +733,11 @@
 RsdCpuScriptIntrinsicBLAS::~RsdCpuScriptIntrinsicBLAS() {
 }
 
-
-
-
-
 RsdCpuScriptImpl * rsdIntrinsic_BLAS(RsdCpuReferenceImpl *ctx,
                                     const Script *s, const Element *e) {
 
     return new RsdCpuScriptIntrinsicBLAS(ctx, s);
 }
+
+} // namespace renderscript
+} // namespace android