Prevented zlib headers messing-up use of the fdopen() function.

modules/juce_core/native/juce_posix_SharedCode.h

@@ -1041,6 +1041,10 @@ public:
     {
         jassert (dest != nullptr);
 
+        #ifdef fdopen
+         #error // the zlib headers define this function as NULL!
+        #endif
+
         if (readHandle == 0 && childPID != 0)
             readHandle = fdopen (pipeHandle, "r");
 

modules/juce_core/zip/juce_GZIPDecompressorInputStream.cpp

@@ -61,6 +61,7 @@ namespace zlibNamespace
   #include "zlib/trees.c"
   #include "zlib/zutil.c"
   #undef Byte
+  #undef fdopen
 
   #if JUCE_CLANG
    #pragma clang diagnostic pop

modules/juce_graphics/image_formats/juce_PNGLoader.cpp

@@ -99,6 +99,7 @@ namespace pnglibNamespace
 
 #undef max
 #undef min
+#undef fdopen
 
 #if JUCE_MSVC
  #pragma warning (pop)