feat: Move all third-party deps into git submodules (#1083)

This also normalizes the structure of all submodule folders so that
there is a clear place to put configurations, outside the submodule
source, but limited in scope to that folder.

Issue #1047 (New build system)

.gitignore

@@ -14,8 +14,3 @@
 .settings
 build/
 /packager/docs/
-/packager/third_party/icu/
-/packager/third_party/libpng/src/
-/packager/third_party/libwebm/src/
-/packager/third_party/modp_b64/
-/packager/third_party/zlib/

.gitmodules

@@ -1,18 +1,33 @@
-[submodule "packager/testing/googletest"]
+[submodule "packager/third_party/googletest/source"]
 	path = packager/third_party/googletest/source
 	url = https://github.com/google/googletest
-[submodule "packager/third_party/abseil-cpp"]
+[submodule "packager/third_party/abseil-cpp/source"]
 	path = packager/third_party/abseil-cpp/source
 	url = https://github.com/abseil/abseil-cpp
-[submodule "packager/third_party/curl"]
+[submodule "packager/third_party/curl/source"]
 	path = packager/third_party/curl/source
 	url = https://github.com/curl/curl
-[submodule "packager/third_party/glog"]
+[submodule "packager/third_party/glog/source"]
 	path = packager/third_party/glog/source
 	url = https://github.com/google/glog
-[submodule "packager/third_party/json"]
-	path = packager/third_party/json
+[submodule "packager/third_party/json/source"]
+	path = packager/third_party/json/source
 	url = https://github.com/nlohmann/json
-[submodule "packager/third_party/mbedtls"]
+[submodule "packager/third_party/mbedtls/source"]
 	path = packager/third_party/mbedtls/source
 	url = https://github.com/Mbed-TLS/mbedtls
+[submodule "packager/third_party/zlib/source"]
+	path = packager/third_party/zlib/source
+	url = https://github.com/joeyparrish/zlib
+[submodule "packager/third_party/libpng/source"]
+	path = packager/third_party/libpng/source
+	url = https://github.com/glennrp/libpng
+[submodule "packager/third_party/libwebm/source"]
+	path = packager/third_party/libwebm/source
+	url = https://github.com/webmproject/libwebm
+[submodule "packager/third_party/libxml2/source"]
+	path = packager/third_party/libxml2/source
+	url = https://gitlab.gnome.org/GNOME/libxml2
+[submodule "packager/third_party/protobuf/source"]
+	path = packager/third_party/protobuf/source
+	url = https://github.com/protocolbuffers/protobuf

packager/third_party/CMakeLists.txt

@@ -31,4 +31,9 @@ add_subdirectory(curl EXCLUDE_FROM_ALL)
 add_subdirectory(glog EXCLUDE_FROM_ALL)
 add_subdirectory(googletest EXCLUDE_FROM_ALL)
 add_subdirectory(json EXCLUDE_FROM_ALL)
+add_subdirectory(libpng EXCLUDE_FROM_ALL)
+add_subdirectory(libwebm EXCLUDE_FROM_ALL)
+add_subdirectory(libxml2 EXCLUDE_FROM_ALL)
 add_subdirectory(mbedtls EXCLUDE_FROM_ALL)
+add_subdirectory(protobuf EXCLUDE_FROM_ALL)
+add_subdirectory(zlib EXCLUDE_FROM_ALL)

packager/third_party/abseil-cpp/CMakeLists.txt

@@ -6,8 +6,6 @@
 
 # CMake build file to host abseil-cpp configuration.
 
-# Variables that must be defined for third-party libraries.
-
 # This will be the new default, so turn it on now to suppress a warning.
 set(ABSL_PROPAGATE_CXX_STD ON)
 

packager/third_party/glog/CMakeLists.txt

@@ -15,5 +15,10 @@ set(WITH_GTEST OFF)
 # Don't depend on or search for libunwind.
 set(WITH_UNWIND OFF)
 
+# Disable this warning/error, which occurs in demangle.c on macOS:
+if(NOT MSVC)
+  add_compile_options(-Wno-shorten-64-to-32)
+endif()
+
 # With these set in scope of this folder, load the library's own CMakeLists.txt.
 add_subdirectory(source)

packager/third_party/json/CMakeLists.txt

@@ -0,0 +1,12 @@
+# Copyright 2022 Google LLC. All rights reserved.
+#
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+# CMake build file to host the nlohmann json library configuration.
+
+# No configuration is currently required.
+
+# With these set in scope of this folder, load the library's own CMakeLists.txt.
+add_subdirectory(source)

packager/third_party/libpng/CMakeLists.txt

@@ -0,0 +1,30 @@
+# Copyright 2022 Google LLC. All rights reserved.
+#
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+# CMake build file to host libpng configuration.
+
+# Turn these features on.
+set(PNG_STATIC ON)
+set(PNG_HARDWARE_OPTIMIZATIONS ON)
+
+# Turn these features off.
+set(PNG_SHARED OFF)
+set(PNG_TESTS OFF)
+set(PNG_FRAMEWORK OFF)
+set(PNG_DEBUG OFF)
+
+# Don't install anything.
+set(SKIP_INSTALL_ALL ON)
+
+# A confusing name, but this means "let us tell you where to find zlib".
+set(PNG_BUILD_ZLIB ON)
+# Tell libpng where to find zlib headers.
+set(ZLIB_INCLUDE_DIR ../zlib/source/)
+# Tell libpng where to find zlib library to link to.
+set(ZLIB_LIBRARY zlibstatic)
+
+# With these set in scope of this folder, load the library's own CMakeLists.txt.
+add_subdirectory(source)