[jvm-packages] XGBoost4j Windows fixes (#1639)

* Changes for Mingw64 compilation to ensure long is a consistent size.

Mainly impacts the Java API which would not compile, but there may be
silent errors on Windows with large datasets before this patch (as long
is 32-bits when compiled with mingw64 even in 64-bit mode).

* Adding ifdefs to ensure it still compiles on MacOS

* Makefile and create_jni.bat changes for Windows.

* Switching XGDMatrixCreateFromCSREx JNI call to use size_t cast

* Fixing lint error, adding profile switching to jvm-packages build to make create-jni.bat get called, adding myself to Contributors.Md

include/xgboost/base.h

@@ -47,7 +47,7 @@ namespace xgboost {
  */
 typedef uint32_t bst_uint;
 /*! \brief long integers */
-typedef unsigned long bst_ulong;  // NOLINT(*)
+typedef uint64_t bst_ulong;  // NOLINT(*)
 /*! \brief float type, used for storing statistics */
 typedef float bst_float;
 

include/xgboost/c_api.h

@@ -24,7 +24,7 @@ XGB_EXTERN_C {
 #endif
 
 // manually define unsign long
-typedef unsigned long bst_ulong;  // NOLINT(*)
+typedef uint64_t bst_ulong;  // NOLINT(*)
 
 /*! \brief handle to DMatrix */
 typedef void *DMatrixHandle;
@@ -40,7 +40,13 @@ typedef struct {
   /*! \brief number of rows in the minibatch */
   size_t size;
   /*! \brief row pointer to the rows in the data */
-  long* offset;  // NOLINT(*)
+#ifdef __APPLE__
+  /* Necessary as Java on MacOS defines jlong as long int
+   * and gcc defines int64_t as long long int. */
+  long* offset; // NOLINT(*)
+#else
+  int64_t* offset;  // NOLINT(*)
+#endif
   /*! \brief labels of each instance */
   float* label;
   /*! \brief weight of each instance, can be NULL */