fix: export zlib symbols (electron#15103)

adill · John Kleinschmidt · commit 47b12eee571c · 2018-10-12T10:17:06.000-04:00
diff --git a/patches/common/zlib/.patches.yaml b/patches/common/zlib/.patches.yaml
@@ -0,0 +1,7 @@
+repo: src
+patches:
+-
+  author: Andy Dill <adill@discordapp.com>
+  file: fix-export_zlib_symbols.patch
+  description: |
+    Set ZLIB_DLL so that we export zlib symbols.
diff --git a/patches/common/zlib/fix-export_zlib_symbols.patch b/patches/common/zlib/fix-export_zlib_symbols.patch
@@ -0,0 +1,15 @@
+diff --git a/third_party/zlib/BUILD.gn b/third_party/zlib/BUILD.gn
+index 902e287f8a0a..c08a187ca968 100644
+--- a/third_party/zlib/BUILD.gn
++++ b/third_party/zlib/BUILD.gn
+@@ -265,6 +265,10 @@ static_library("zlib") {
+   defines = []
+   deps = []
+
++  if (is_win) {
++    defines += [ "ZLIB_DLL" ]
++  }
++
+   if (!is_ios && (current_cpu == "x86" || current_cpu == "x64")) {
+     deps += [ ":zlib_crc32_simd" ]
+
