For vendored builds use the jpeg and zlib submodules instead of bundled sources

Author: ancwrd1

.gitmodules

@@ -1,3 +1,9 @@
 [submodule "qpdf-sys/qpdf"]
 	path = qpdf-sys/qpdf
 	url = https://github.com/qpdf/qpdf
+[submodule "qpdf-sys/zlib"]
+	path = qpdf-sys/zlib
+	url = https://github.com/madler/zlib.git
+[submodule "qpdf-sys/jpeg"]
+	path = qpdf-sys/jpeg
+	url = https://github.com/libjpeg-turbo/ijg.git

qpdf-sys/build.rs

@@ -221,8 +221,8 @@ fn build_qpdf() {
 
     build
         .cpp(true)
-        .include(root.join("zlib-1.3.1"))
-        .include(root.join("jpeg-9d"))
+        .include(root.join("zlib"))
+        .include(root.join("jpeg"))
         .include(root.join("qpdf").join("include"))
         .include(root.join("qpdf").join("libqpdf"))
         .files(
@@ -262,8 +262,8 @@ fn build_bindings() {
 #[cfg(feature = "vendored")]
 fn main() {
     build_bindings();
-    build_cc("zlib", "zlib-1.3.1", ZLIB_SRC);
-    build_cc("jpeg", "jpeg-9d", JPEG_SRC);
+    build_cc("zlib", "zlib", ZLIB_SRC);
+    build_cc("jpeg", "jpeg", JPEG_SRC);
     build_qpdf();
 }