raster/r.statistics: Fix Resource Leak issues (#5077)

Author: ShubhamDesai

raster/r.statistics/o_kurt.c

@@ -70,6 +70,7 @@ int o_kurt(const char *basemap, const char *covermap, const char *outputmap,
 
     G_popen_close(&stats_child);
     G_popen_close(&reclass_child);
+    G_free(tab);
 
     return 0;
 }

raster/r.statistics/o_sdev.c

@@ -71,6 +71,7 @@ int o_sdev(const char *basemap, const char *covermap, const char *outputmap,
 
     G_popen_close(&stats_child);
     G_popen_close(&reclass_child);
+    G_free(tab);
 
     return 0;
 }

raster/r.statistics/o_skew.c

@@ -70,6 +70,7 @@ int o_skew(const char *basemap, const char *covermap, const char *outputmap,
 
     G_popen_close(&stats_child);
     G_popen_close(&reclass_child);
+    G_free(tab);
 
     return 0;
 }

raster/r.statistics/o_var.c

@@ -73,6 +73,7 @@ int o_var(const char *basemap, const char *covermap, const char *outputmap,
 
     G_popen_close(&stats_child);
     G_popen_close(&reclass_child);
+    G_free(tab);
 
     return 0;
 }