[ObjC] rename the file to drop the "objectivec_" prefix.

Since "names.(h|cc)" now exists, drop the prefixing on all the files.

objectivec/DevTools/check_version_stamps.sh

diff --git a/objectivec/DevTools/check_version_stamps.sh b/objectivec/DevTools/check_version_stamps.sh
index a3524cb..5972e35 100755
--- a/objectivec/DevTools/check_version_stamps.sh
+++ b/objectivec/DevTools/check_version_stamps.sh
@@ -16,7 +16,7 @@
     exit 1
 }
 
-readonly GeneratorSrc="${ProtoRootDir}/src/google/protobuf/compiler/objectivec/objectivec_file.cc"
+readonly GeneratorSrc="${ProtoRootDir}/src/google/protobuf/compiler/objectivec/file.cc"
 readonly RuntimeSrc="${ProtoRootDir}/objectivec/GPBBootstrap.h"
 
 check_constant() {

objectivec/GPBDescriptor.m

diff --git a/objectivec/GPBDescriptor.m b/objectivec/GPBDescriptor.m
index 72368ce..316ce76 100644
--- a/objectivec/GPBDescriptor.m
+++ b/objectivec/GPBDescriptor.m
@@ -681,7 +681,7 @@
   }
 
   // The logic here has to match SetCommonFieldVariables() from
-  // objectivec_field.cc in the proto compiler.
+  // objectivec/field.cc in the proto compiler.
   NSString *name = self.name;
   NSUInteger len = [name length];
 
@@ -918,7 +918,7 @@
   if (extraTextFormatInfo_) {
     result = GPBDecodeTextFormatName(extraTextFormatInfo_, (int32_t)index, shortName);
   }
-  // Logic here needs to match what objectivec_enum.cc does in the proto
+  // Logic here needs to match what objectivec/enum.cc does in the proto
   // compiler.
   if (result == nil) {
     NSUInteger len = [shortName length];

objectivec/Tests/GPBMessageTests.m

diff --git a/objectivec/Tests/GPBMessageTests.m b/objectivec/Tests/GPBMessageTests.m
index 83b8d11..7d4cf79 100644
--- a/objectivec/Tests/GPBMessageTests.m
+++ b/objectivec/Tests/GPBMessageTests.m
@@ -1843,8 +1843,8 @@
 }
 
 - (void)testPropertyNaming {
-  // objectivec_helpers.cc has some special handing to get proper all caps
-  // for a few cases to meet objc developer expectations.
+  // names.cc has some special handing to get proper all caps for a few cases to
+  // meet objc developer expectations.
   //
   // This "test" confirms that the expected names are generated, otherwise the
   // test itself will fail to compile.
@@ -1861,7 +1861,7 @@
 }
 
 - (void)testEnumNaming {
-  // objectivec_helpers.cc has some interesting cases to deal with in
+  // names.cc has some interesting cases to deal with in
   // EnumValueName/EnumValueShortName.  Confirm that things generated as
   // expected.
 
@@ -1966,9 +1966,8 @@
 }
 
 - (void)testReservedWordNaming {
-  // objectivec_helpers.cc has some special handing to make sure that
-  // some "reserved" objc names get renamed in a way so they
-  // don't conflict.
+  // names.cc has some special handing to make sure that some "reserved" objc
+  // names get renamed in a way so they don't conflict.
   //
   // This "test" confirms that the expected names are generated,
   // otherwise the test itself will fail to compile.