MCOL-5199 This patch solves the overal performance degradation introduced with a new way of char columns hashing

in aggregation code
The patch disables padding that forces hasher to calculate over the whole 2k buffer. This patch also moves hashing code
into the common place where it belongs.

dbcon/mysql/ha_mcs_sysvars.cpp

@@ -39,6 +39,8 @@ static MYSQL_THDVAR_ENUM(compression_type, PLUGIN_VAR_RQCMDARG,
                          "SNAPPY segment files are Snappy compressed (default);"
 #ifdef HAVE_LZ4
                          "LZ4 segment files are LZ4 compressed;",
+# else
+			 ,
 #endif
                          NULL,                              // check
                          NULL,                              // update