PAGE_SIZE shouldn't be unsigned

Fixes #2559

Author: chearon

CHANGELOG.md

@@ -10,6 +10,7 @@ project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 ### Added
 ### Fixed
+* Fix building with gcc (#2559)
 
 3.2.2
 ==================

src/Canvas.cc

@@ -643,7 +643,7 @@ Canvas::StreamPDFSync(const Napi::CallbackInfo& info) {
 static uint32_t getSafeBufSize(Canvas* canvas) {
   // Don't allow the buffer size to exceed the size of the canvas (#674)
   // TODO not sure if this is really correct, but it fixed #674
-  return (std::min)((uint32_t)canvas->getWidth() * canvas->getHeight() * 4, PAGE_SIZE);
+  return (std::min)((uint32_t)canvas->getWidth() * canvas->getHeight() * 4, (uint32_t)PAGE_SIZE);
 }
 
 void

src/closure.h

@@ -19,7 +19,7 @@ class Canvas;
 #include <vector>
 
 #ifndef PAGE_SIZE
-  #define PAGE_SIZE 4096u
+  #define PAGE_SIZE 4096
 #endif
 
 /*