Audio V4: Update namespace and version of 4.0 shim

Put the shim in a V4_0 namespace to comply with the ODR.
Make the include guard unique.
Split from the error prone interface adaptation change for safer review.

Patch generated with:
sed -i 's/V2_0/V4_0/g' *
sed -i "/include.*2.0/s/2\.0/4.0/" *
sed -i '/namespace android *{/anamespace V4_0 {' *
sed -Ei 's/(ifndef|define|endif)(.*)_H/\1\2_4_0_H/' *
sed -Ei 's#}(.*)namespace android$#}\1namespace V4_0\n\0#' *

Bug: 38184704
Test: Compile
Change-Id: I7d3aa46b3dfec664cbeea8a6b946456b8e8f06e3
Merged-In: I7d3aa46b3dfec664cbeea8a6b946456b8e8f06e3
Cherry-picked from master
Signed-off-by: Kevin Rocard <krocard@google.com>
diff --git a/media/libaudiohal/4.0/EffectBufferHalHidl.cpp b/media/libaudiohal/4.0/EffectBufferHalHidl.cpp
index 226a500..957c89f 100644
--- a/media/libaudiohal/4.0/EffectBufferHalHidl.cpp
+++ b/media/libaudiohal/4.0/EffectBufferHalHidl.cpp
@@ -30,6 +30,7 @@
 using ::android::hidl::allocator::V1_0::IAllocator;
 
 namespace android {
+namespace V4_0 {
 
 // static
 uint64_t EffectBufferHalHidl::makeUniqueId() {
@@ -141,4 +142,5 @@
     memcpy(mExternalData, mAudioBuffer.raw, size);
 }
 
+} // namespace V4_0
 } // namespace android