Override CocoaPods module to lowercase (protocolbuffers#6464)

Fix protocolbuffers#3218

Author: paulb777

Protobuf.podspec

@@ -5,13 +5,14 @@
 # dependent projects use the :git notation to refer to the library.
 Pod::Spec.new do |s|
   s.name     = 'Protobuf'
-  s.version  = '3.9.0-rc1'
+  s.version  = '3.9.0-rc2'
   s.summary  = 'Protocol Buffers v.3 runtime library for Objective-C.'
   s.homepage = 'https://github.com/protocolbuffers/protobuf'
   s.license  = '3-Clause BSD License'
   s.authors  = { 'The Protocol Buffers contributors' => '[email protected]' }
   s.cocoapods_version = '>= 1.0'
 
+  s.module_name = 'protobuf'
   s.source = { :git => 'https://github.com/protocolbuffers/protobuf.git',
                :tag => "v#{s.version}" }
 

objectivec/GPBProtocolBuffers.h

@@ -52,16 +52,16 @@
 
 // Well-known proto types
 #if GPB_USE_PROTOBUF_FRAMEWORK_IMPORTS
- #import <Protobuf/Any.pbobjc.h>
- #import <Protobuf/Api.pbobjc.h>
- #import <Protobuf/Duration.pbobjc.h>
- #import <Protobuf/Empty.pbobjc.h>
- #import <Protobuf/FieldMask.pbobjc.h>
- #import <Protobuf/SourceContext.pbobjc.h>
- #import <Protobuf/Struct.pbobjc.h>
- #import <Protobuf/Timestamp.pbobjc.h>
- #import <Protobuf/Type.pbobjc.h>
- #import <Protobuf/Wrappers.pbobjc.h>
+ #import <protobuf/Any.pbobjc.h>
+ #import <protobuf/Api.pbobjc.h>
+ #import <protobuf/Duration.pbobjc.h>
+ #import <protobuf/Empty.pbobjc.h>
+ #import <protobuf/FieldMask.pbobjc.h>
+ #import <protobuf/SourceContext.pbobjc.h>
+ #import <protobuf/Struct.pbobjc.h>
+ #import <protobuf/Timestamp.pbobjc.h>
+ #import <protobuf/Type.pbobjc.h>
+ #import <protobuf/Wrappers.pbobjc.h>
 #else
  #import "google/protobuf/Any.pbobjc.h"
  #import "google/protobuf/Api.pbobjc.h"

objectivec/GPBWellKnownTypes.h

@@ -37,9 +37,9 @@
 #endif
 
 #if GPB_USE_PROTOBUF_FRAMEWORK_IMPORTS
- #import <Protobuf/Any.pbobjc.h>
- #import <Protobuf/Duration.pbobjc.h>
- #import <Protobuf/Timestamp.pbobjc.h>
+ #import <protobuf/Any.pbobjc.h>
+ #import <protobuf/Duration.pbobjc.h>
+ #import <protobuf/Timestamp.pbobjc.h>
 #else
  #import "google/protobuf/Any.pbobjc.h"
  #import "google/protobuf/Duration.pbobjc.h"

objectivec/google/protobuf/Any.pbobjc.h

@@ -981,7 +981,7 @@ string BuildCommentsString(const SourceLocation& location,
 // want to put the library in a framework is an interesting question. The
 // problem is it means changing sources shipped with the library to actually
 // use a different value; so it isn't as simple as a option.
-const char* const ProtobufLibraryFrameworkName = "Protobuf";
+const char* const ProtobufLibraryFrameworkName = "protobuf";
 
 string ProtobufFrameworkImportSymbol(const string& framework_name) {
   // GPB_USE_[framework_name]_FRAMEWORK_IMPORTS