Address Linux build errors caused by missing size_t definition

Also prevent warning due to calling free on a const char * in PDALLoadPipeline.

Author: jimmysoda

source/pdal/pdalc_config.h

@@ -46,6 +46,7 @@ namespace capi
 extern "C"
 {
 #else
+#include <stddef.h>
 #include <stdbool.h>
 #endif
 /**

tests/pdal/test_pdalc_utils.c

@@ -32,7 +32,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 
-const char *PDALReadPipelineJson(const char *path)
+char *PDALReadPipelineJson(const char *path)
 {
     FILE *file = fopen(path, "rb");
     char *json = NULL;
@@ -64,7 +64,7 @@ const char *PDALReadPipelineJson(const char *path)
 PDALPipelinePtr *PDALLoadPipeline(const char *path)
 {
     PDALPipelinePtr *pipeline = NULL;
-    const char *json = PDALReadPipelineJson(path);
+    char *json = PDALReadPipelineJson(path);
 
     if (json)
     {

tests/pdal/test_pdalc_utils.h

@@ -38,7 +38,7 @@
  * @param path The path to the PDAL pipeline JSON file
  * @return The contents of the PDAL pipeline JSON file as a string
  */
-const char *PDALReadPipelineJson(const char *path);
+char *PDALReadPipelineJson(const char *path);
 
 /**
  * Creates a PDAL pipeline from the provided path and attempts to execute it.