[build] Use subproject for zlib

.gitmodules

@@ -10,7 +10,3 @@
 	path = third_party/lz4
 	url = https://github.com/lz4/lz4.git
 	ignore = dirty
-[submodule "third_party/zlib"]
-	path = third_party/zlib
-	url = https://github.com/madler/zlib.git
-	ignore = dirty

meson.build

@@ -86,40 +86,9 @@ libwoff2 = library('woff2',
 )
 
 
-libz = library('z',
-  'third_party/zlib/adler32.c',
-  'third_party/zlib/compress.c',
-  'third_party/zlib/crc32.c',
-  'third_party/zlib/crc32.h',
-  'third_party/zlib/deflate.c',
-  'third_party/zlib/deflate.h',
-  'third_party/zlib/gzclose.c',
-  'third_party/zlib/gzguts.h',
-  'third_party/zlib/gzlib.c',
-  'third_party/zlib/gzread.c',
-  'third_party/zlib/gzwrite.c',
-  'third_party/zlib/infback.c',
-  'third_party/zlib/inffast.c',
-  'third_party/zlib/inffast.h',
-  'third_party/zlib/inffixed.h',
-  'third_party/zlib/inflate.c',
-  'third_party/zlib/inflate.h',
-  'third_party/zlib/inftrees.c',
-  'third_party/zlib/inftrees.h',
-  'third_party/zlib/trees.c',
-  'third_party/zlib/trees.h',
-  'third_party/zlib/uncompr.c',
-  'third_party/zlib/zconf.h',
-  'third_party/zlib/zlib.h',
-  'third_party/zlib/zutil.c',
-  'third_party/zlib/zutil.h',
-)
-
-
 ots_includes = [
   'include',
   'third_party/woff2/include',
-  'third_party/zlib',
 ]
 
 ots_sources = [
@@ -185,7 +154,7 @@ ots_sources = [
   'src/vorg.h',
 ]
 
-ots_libs = [libbrotli, libwoff2, libz]
+ots_libs = [libbrotli, libwoff2]
 
 if get_option('graphite')
   ots_includes += ['third_party/lz4/lib']
@@ -234,10 +203,13 @@ if get_option('variations')
   ]
 endif
 
+zlib = dependency('zlib', fallback : ['zlib', 'zlib_dep'])
+
 libots = library('ots',
   ots_sources,
   include_directories: include_directories(ots_includes),
   link_with: ots_libs,
+  dependencies: zlib,
 )
 
 

subprojects/.gitignore

@@ -1,2 +1,2 @@
 /packagecache
-/*-release*
+/*-*