tdf#109104: respect RFC3986 for newlines in ScEncodeURL

Quotation of RFC3986:
A percent-encoded octet is encoded as a character
triplet, consisting of the percent character "%" followed by the two
hexadecimal digits representing that octet's numeric value
So test the length of the return of OString::number and add "0" if needed

ScEncodeURL was added with:
https://cgit.freedesktop.org/libreoffice/core/commit/?id=25434372bf56e0ebdb7e7d47ab3c14c68211509f

Thank you to Bele (the bugtracker reporter) for code pointer!

Change-Id: I8df102eb38b31933c6ebb15bb25c125b423f722b
Reviewed-on: https://gerrit.libreoffice.org/41086Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Eike Rathke <erack@redhat.com>

sc/source/core/tool/interpr7.cxx

@@ -325,7 +325,14 @@ void ScInterpreter::ScEncodeURL()
             else
             {
                 aUrlBuf.append( '%' );
-                aUrlBuf.append( OString::number( static_cast<unsigned char>( c ), 16 ).toAsciiUpperCase() );
+                OString convertedChar = OString::number( static_cast<unsigned char>( c ), 16 ).toAsciiUpperCase();
+                // RFC 3986 indicates:
+                // "A percent-encoded octet is encoded as a character triplet,
+                // consisting of the percent character "%" followed by the two hexadecimal digits
+                // representing that octet's numeric value"
+                if (convertedChar.getLength() == 1)
+                    aUrlBuf.append("0");
+                aUrlBuf.append(convertedChar);
             }
         }
         PushString( OUString::fromUtf8( aUrlBuf.makeStringAndClear() ) );