libwebp: Don't define WEBP_DLL macro when building a static library

Before it would define the WEBP_DLL macro unconditionally, which caused it to use the __declspec(dllexport) property when building as a static library on Windows. That caused its symbols to be exported from any target which the static libwebp was linked into (such as an executable).

releases.json

@@ -2083,6 +2083,7 @@
       "libwebpmux"
     ],
     "versions": [
+      "1.3.2-2",
       "1.3.2-1",
       "1.3.1-2",
       "1.3.1-1"

subprojects/packagefiles/libwebp/meson.build

@@ -94,7 +94,11 @@ pkg = import('pkgconfig')
 
 m_dep = cc.find_library('m', required: false)
 
-add_project_arguments('-DHAVE_CONFIG_H', '-DWEBP_DLL', language: 'c')
+add_project_arguments('-DHAVE_CONFIG_H', language: 'c')
+
+if get_option('default_library') != 'static'
+  add_project_arguments('-DWEBP_DLL', language: 'c')
+endif
 
 top_includes = include_directories('.', 'src')