Fix build with OpenEXR>=3

Index: src-IL/src/il_exr.cpp
--- src-IL/src/il_exr.cpp.orig
+++ src-IL/src/il_exr.cpp
@@ -143,9 +143,9 @@ bool ilIStream::read(char c[], int n)
 
 
 //@TODO: Make this work with 64-bit values.
-Imf::Int64 ilIStream::tellg()
+uint64_t ilIStream::tellg()
 {
-	Imf::Int64 Pos;
+	uint64_t Pos;
 
 	// itell only returns a 32-bit value!
 	Pos = itell();
@@ -156,7 +156,7 @@ Imf::Int64 ilIStream::tellg()
 
 // Note that there is no return value here, even though there probably should be.
 //@TODO: Make this work with 64-bit values.
-void ilIStream::seekg(Imf::Int64 Pos)
+void ilIStream::seekg(uint64_t Pos)
 {
 	// iseek only uses a 32-bit value!
 	iseek((ILint)Pos, IL_SEEK_SET);  // I am assuming this is seeking from the beginning.
@@ -309,9 +309,9 @@ void ilOStream::write(const char c[], int n)
 }
 
 //@TODO: Make this work with 64-bit values.
-Imf::Int64 ilOStream::tellp()
+uint64_t ilOStream::tellp()
 {
-	Imf::Int64 Pos;
+	uint64_t Pos;
 
 	// itellw only returns a 32-bit value!
 	Pos = itellw();
@@ -321,7 +321,7 @@ Imf::Int64 ilOStream::tellp()
 
 // Note that there is no return value here, even though there probably should be.
 //@TODO: Make this work with 64-bit values.
-void ilOStream::seekp(Imf::Int64 Pos)
+void ilOStream::seekp(uint64_t Pos)
 {
 	// iseekw only uses a 32-bit value!
 	iseekw((ILint)Pos, IL_SEEK_SET);  // I am assuming this is seeking from the beginning.