Externals: Add zstd

I had to rename Source/Common/Compiler.h because the VS build
confuses it with Externals/zstd/lib/common/compiler.h otherwise.

Externals/zstd/CMakeLists.txt

@@ -0,0 +1,127 @@
+project(bzip2 C)
+
+include(CheckTypeSize)
+include(CheckFunctionExists)
+include(CheckIncludeFile)
+include(CheckCSourceCompiles)
+
+check_include_file(sys/types.h HAVE_SYS_TYPES_H)
+check_include_file(stdint.h    HAVE_STDINT_H)
+check_include_file(stddef.h    HAVE_STDDEF_H)
+
+# Check to see if we have large file support
+set(CMAKE_REQUIRED_DEFINITIONS -D_LARGEFILE64_SOURCE=1)
+# We add these other definitions here because CheckTypeSize.cmake
+# in CMake 2.4.x does not automatically do so and we want
+# compatibility with CMake 2.4.x.
+if(HAVE_SYS_TYPES_H)
+    list(APPEND CMAKE_REQUIRED_DEFINITIONS -DHAVE_SYS_TYPES_H)
+endif()
+if(HAVE_STDINT_H)
+    list(APPEND CMAKE_REQUIRED_DEFINITIONS -DHAVE_STDINT_H)
+endif()
+if(HAVE_STDDEF_H)
+    list(APPEND CMAKE_REQUIRED_DEFINITIONS -DHAVE_STDDEF_H)
+endif()
+check_type_size(off64_t OFF64_T)
+if(HAVE_OFF64_T)
+   add_definitions(-D_LARGEFILE64_SOURCE=1)
+endif()
+set(CMAKE_REQUIRED_DEFINITIONS) # clear variable
+
+# Check for fseeko
+check_function_exists(fseeko HAVE_FSEEKO)
+if(NOT HAVE_FSEEKO)
+    add_definitions(-DNO_FSEEKO)
+endif()
+
+#
+# Check for unistd.h
+#
+check_include_file(unistd.h HAVE_UNISTD_H)
+if(HAVE_UNISTD_H)
+    add_definitions(-DHAVE_UNISTD_H)
+endif()
+
+if(MSVC)
+    add_definitions(-D_CRT_SECURE_NO_DEPRECATE)
+    add_definitions(-D_CRT_NONSTDC_NO_DEPRECATE)
+endif()
+
+# Always hide XXHash symbols
+add_definitions(-DXXH_NAMESPACE=ZSTD_)
+
+#============================================================================
+# zstd
+#============================================================================
+
+set(ZSTD_PUBLIC_HDRS
+    lib/zstd.h
+)
+set(ZSTD_PRIVATE_HDRS
+    lib/common/bitstream.h
+    lib/common/compiler.h
+    lib/common/cpu.h
+    lib/common/debug.h
+    lib/common/error_private.h
+    lib/common/fse.h
+    lib/common/huf.h
+    lib/common/mem.h
+    lib/common/pool.h
+    lib/common/threading.h
+    lib/common/xxhash.h
+    lib/common/zstd_errors.h
+    lib/common/zstd_internal.h
+    lib/compress/hist.h
+    lib/compress/zstd_compress_internal.h
+    lib/compress/zstd_compress_literals.h
+    lib/compress/zstd_compress_sequences.h
+    lib/compress/zstd_cwksp.h
+    lib/compress/zstd_double_fast.h
+    lib/compress/zstd_fast.h
+    lib/compress/zstd_lazy.h
+    lib/compress/zstd_ldm.h
+    lib/compress/zstd_opt.h
+    lib/compress/zstdmt_compress.h
+    lib/decompress/zstd_ddict.h
+    lib/decompress/zstd_decompress_block.h
+    lib/decompress/zstd_decompress_internal.h
+)
+set(ZSTD_SRCS
+    lib/common/debug.c
+    lib/common/entropy_common.c
+    lib/common/error_private.c
+    lib/common/fse_decompress.c
+    lib/common/pool.c
+    lib/common/threading.c
+    lib/common/xxhash.c
+    lib/common/zstd_common.c
+    lib/compress/fse_compress.c
+    lib/compress/hist.c
+    lib/compress/huf_compress.c
+    lib/compress/zstd_compress.c
+    lib/compress/zstd_compress_literals.c
+    lib/compress/zstd_compress_sequences.c
+    lib/compress/zstd_double_fast.c
+    lib/compress/zstd_fast.c
+    lib/compress/zstd_lazy.c
+    lib/compress/zstd_ldm.c
+    lib/compress/zstd_opt.c
+    lib/compress/zstdmt_compress.c
+    lib/decompress/huf_decompress.c
+    lib/decompress/zstd_ddict.c
+    lib/decompress/zstd_decompress.c
+    lib/decompress/zstd_decompress_block.c
+)
+
+add_library(zstd STATIC ${ZSTD_SRCS} ${ZSTD_PUBLIC_HDRS} ${ZSTD_PRIVATE_HDRS})
+add_library(zstd::zstd ALIAS zstd)
+
+target_include_directories(zstd
+PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}/lib
+PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}/lib/common
+    ${CMAKE_CURRENT_SOURCE_DIR}/lib/compress
+    ${CMAKE_CURRENT_SOURCE_DIR}/lib/decompress
+)