[folly] Add a dependency on PYTHON3 (the tool)

Rebase patch list to be compatible with previous portfile versions.

ports/folly/CONTROL

@@ -1,4 +1,4 @@
 Source: folly
-Version: v2017.05.08.00-1
+Version: v2017.05.08.00-2
 Description: An open-source C++ library developed and used at Facebook. The library is UNSTABLE on Windows
 Build-Depends: zlib, openssl, boost, libevent, double-conversion, glog, gflags, lz4, liblzma, snappy

ports/folly/fix-cmakelists.patch

@@ -1,44 +1,38 @@
+diff --git a/CMake/folly-deps.cmake b/CMake/folly-deps.cmake
+index 211c6fbf..988225a2 100755
+--- a/CMake/folly-deps.cmake
++++ b/CMake/folly-deps.cmake
+@@ -11,8 +11,8 @@ find_package(Boost 1.55.0 MODULE
+   REQUIRED
+ )
+ find_package(DoubleConversion MODULE REQUIRED)
+-find_package(GFlags MODULE REQUIRED)
+-find_package(GLog MODULE REQUIRED)
++find_package(gflags CONFIG REQUIRED)
++find_package(glog CONFIG REQUIRED)
+ find_package(LibEvent MODULE REQUIRED)
+ find_package(OpenSSL MODULE REQUIRED)
+ find_package(PThread MODULE)
 diff --git a/CMakeLists.txt b/CMakeLists.txt
-index 38886d65..00e5307c 100755
+index 38886d65..4c796eac 100755
 --- a/CMakeLists.txt
 +++ b/CMakeLists.txt
-@@ -1,15 +1,14 @@
+@@ -1,15 +1,8 @@
  cmake_minimum_required(VERSION 3.4.0 FATAL_ERROR)
 
 -# Unfortunately, CMake doesn't easily provide us a way to merge static
 -# libraries, which is what we want to do to generate the main folly library, so
 -# we do a bit of a workaround here to inject a property into the generated
 -# project files that will only get enabled for the folly target. Ugly, but
 -# the alternatives are far, far worse.
--if ("${CMAKE_GENERATOR}" MATCHES "Visual Studio 15( 2017)? Win64")
+ if ("${CMAKE_GENERATOR}" MATCHES "Visual Studio 15( 2017)? Win64")
 -  set(CMAKE_GENERATOR_TOOLSET "v141</PlatformToolset></PropertyGroup><ItemDefinitionGroup Condition=\"'$(ProjectName)'=='folly'\"><ProjectReference><LinkLibraryDependencies>true</LinkLibraryDependencies></ProjectReference></ItemDefinitionGroup><PropertyGroup><PlatformToolset>v141")
-+project(${PACKAGE_NAME} CXX)
-+
-+if (NOT ${MSVC_CXX_ARCHITECTURE_ID} STREQUAL "x64")
-+  message(FATAL_ERROR "This build script only supports building Folly on 64-bit Windows.")
-+endif()
-+
-+if (MSVC_VERSION EQUAL 1910)
    set(MSVC_IS_2017 ON)
--elseif ("${CMAKE_GENERATOR}" STREQUAL "Visual Studio 14 2015 Win64")
+ elseif ("${CMAKE_GENERATOR}" STREQUAL "Visual Studio 14 2015 Win64")
 -  set(CMAKE_GENERATOR_TOOLSET "v140</PlatformToolset></PropertyGroup><ItemDefinitionGroup Condition=\"'$(ProjectName)'=='folly'\"><ProjectReference><LinkLibraryDependencies>true</LinkLibraryDependencies></ProjectReference></ItemDefinitionGroup><PropertyGroup><PlatformToolset>v140")
-+elseif (MSVC_VERSION EQUAL 1900)
    set(MSVC_IS_2017 OFF)
  else()
    message(FATAL_ERROR "This build script only supports building Folly on 64-bit Windows with Visual Studio 2015 or Visual Studio 2017.")
-@@ -29,12 +28,6 @@ set(PACKAGE_BUGREPORT "https://github.com/facebook/folly/issues")
- # 150+ tests in the root folder anyone? No? I didn't think so.
- set_property(GLOBAL PROPERTY USE_FOLDERS ON)
-
--project(${PACKAGE_NAME} CXX)
--
--# Check architecture OS
--if (NOT CMAKE_SIZEOF_VOID_P EQUAL 8)
--  message(FATAL_ERROR "Folly requires a 64bit OS")
--endif()
- if(NOT "${CMAKE_SYSTEM_NAME}" STREQUAL "Windows")
-   message(FATAL_ERROR "You should only be using CMake to build Folly if you are on Windows!")
- endif()
 @@ -122,7 +115,8 @@ add_library(folly_base STATIC
  )
  auto_source_group(folly ${FOLLY_DIR} ${files} ${hfiles})

ports/folly/fix-generators.patch

@@ -0,0 +1,36 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 4c796ea..684f48f 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -1,13 +1,5 @@
+ cmake_minimum_required(VERSION 3.4.0 FATAL_ERROR)
+
+-if ("${CMAKE_GENERATOR}" MATCHES "Visual Studio 15( 2017)? Win64")
+-  set(MSVC_IS_2017 ON)
+-elseif ("${CMAKE_GENERATOR}" STREQUAL "Visual Studio 14 2015 Win64")
+-  set(MSVC_IS_2017 OFF)
+-else()
+-  message(FATAL_ERROR "This build script only supports building Folly on 64-bit Windows with Visual Studio 2015 or Visual Studio 2017.")
+-endif()
+-
+ # includes
+ set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/CMake" ${CMAKE_MODULE_PATH})
+ include_directories(${CMAKE_CURRENT_SOURCE_DIR})
+@@ -24,10 +16,14 @@ set_property(GLOBAL PROPERTY USE_FOLDERS ON)
+
+ project(${PACKAGE_NAME} CXX)
+
+-# Check architecture OS
+-if (NOT CMAKE_SIZEOF_VOID_P EQUAL 8)
+-  message(FATAL_ERROR "Folly requires a 64bit OS")
++if (NOT MSVC_VERSION LESS 1910)
++  set(MSVC_IS_2017 ON)
++elseif (NOT MSVC_VERSION LESS 1900)
++  set(MSVC_IS_2017 OFF)
++else()
++  message(FATAL_ERROR "This build script only supports building Folly on 64-bit Windows with Visual Studio 2015 or Visual Studio 2017.")
+ endif()
++
+ if(NOT "${CMAKE_SYSTEM_NAME}" STREQUAL "Windows")
+   message(FATAL_ERROR "You should only be using CMake to build Folly if you are on Windows!")
+ endif()

ports/folly/portfile.cmake

@@ -9,6 +9,11 @@ endif()
 
 include(vcpkg_common_functions)
 
+# Required to run build/generate_escape_tables.py et al.
+vcpkg_find_acquire_program(PYTHON3)
+get_filename_component(PYTHON3_DIR "${PYTHON3}" DIRECTORY)
+set(ENV{PATH} "$ENV{PATH};${PYTHON3_DIR}")
+
 vcpkg_from_github(
     OUT_SOURCE_PATH SOURCE_PATH
     REPO facebook/folly
@@ -20,7 +25,7 @@ vcpkg_from_github(
 vcpkg_apply_patches(
     SOURCE_PATH ${SOURCE_PATH}
     PATCHES "${CMAKE_CURRENT_LIST_DIR}/fix-cmakelists.patch"
-    PATCHES "${CMAKE_CURRENT_LIST_DIR}/fix-deps.patch"
+    PATCHES "${CMAKE_CURRENT_LIST_DIR}/fix-generators.patch"
 )
 
 if(VCPKG_CRT_LINKAGE STREQUAL static)