Bug#45197 cp1250 character set with IBMDB2I generates 2027 error

Running a SELECT query over an IBMDB2I table with a cp1250 character set
was producing an error 2027 (ibmdb2i error 2027: Error converting single-byte
sort sequence to UCS-2).

The QMY_DESCRIBE_RANGE API was returning error 2027 to the storage engine
because the CCSID used for a cp1250 column (870) does not match the CCSID
used by the DB2 sort sequences associated with cp1250_* collations (1153).
This was because the storage engine relies on a set of system APIs to
determine which CCSID value most closely matches a particular MySQL
character set. However, in the case of cp1250, the system is returning
CCSID 870, which does not have a codepoint for the euro symbol, making it
an incorrect match.

This patch overrides the selection of a compatible CCSID to always return
1153 for cp1250.

storage/ibmdb2i/db2i_charsetSupport.cc

@@ -245,11 +245,16 @@ static int32 getNewTextDesc(const int32 inType,
   else if ((inType == Qlg_TypeAS400CCSID) && (outType == Qlg_TypeAix41))
   {
     // Override non-standard charsets
-    if (unlikely(strcmp("1148", in) == 0))
+    if (strcmp("1148", in) == 0)
     {
       strcpy(out, "IBM-1148");
       DBUG_RETURN(0);
     }
+    else if (unlikely(strcmp("1153", in) == 0))
+    {
+      strcpy(out, "IBM-1153");
+      DBUG_RETURN(0);
+    }
   }
 
   char argBuf[sizeof(ArgList)+15];
@@ -583,6 +588,11 @@ int32 getAssociatedCCSID(const uint16 inCcsid, const int inEncodingScheme, uint1
     *outCcsid = 1148;
     DBUG_RETURN(0);
   }
+  else if ((inCcsid == 1250) && (inEncodingScheme == 0x1100))
+  {
+    *outCcsid = 1153;
+    DBUG_RETURN(0);
+  }
 
   if (!ptrInited)
   {