Remove unused files from src/klib (#19415)

Author: jbrockmendel

pandas/_libs/src/klib/ktypes.h

@@ -44,7 +44,6 @@ Numeric decoder derived from from TCL library
 #include <numpy/arrayobject.h>    // NOLINT(build/include_order)
 #include <numpy/arrayscalars.h>   // NOLINT(build/include_order)
 #include <numpy/npy_math.h>       // NOLINT(build/include_order)
-#include <numpy_helper.h>         // NOLINT(build/include_order)
 #include <stdio.h>                // NOLINT(build/include_order)
 #include <ultrajson.h>            // NOLINT(build/include_order)
 #include <np_datetime.h>          // NOLINT(build/include_order)
@@ -60,6 +59,8 @@ static PyTypeObject *cls_series;
 static PyTypeObject *cls_index;
 static PyTypeObject *cls_nat;
 
+npy_int64 get_nat(void) { return NPY_MIN_INT64; }
+
 typedef void *(*PFN_PyTypeToJSON)(JSOBJ obj, JSONTypeContext *ti,
                                   void *outValue, size_t *_outLen);
 

pandas/_libs/src/klib/kvec.h

@@ -694,10 +694,9 @@ def pxd(name):
                                 'pandas/_libs/src/ujson/lib/ultrajsonenc.c',
                                 'pandas/_libs/src/ujson/lib/ultrajsondec.c'] +
                                np_datetime_sources),
-                      include_dirs=(['pandas/_libs/src/ujson/python',
-                                     'pandas/_libs/src/ujson/lib',
-                                     'pandas/_libs/src/datetime'] +
-                                    common_include),
+                      include_dirs=['pandas/_libs/src/ujson/python',
+                                    'pandas/_libs/src/ujson/lib',
+                                    'pandas/_libs/src/datetime'],
                       extra_compile_args=(['-D_GNU_SOURCE'] +
                                           extra_compile_args))