Extension shared library components must not use the "prefix" feature

...at least no non-bundled ones, see 9dfcee9266c9769153444cdcd4ab0e6e636c3eb6
"Not being able to honor a 'prefix' is a rather hard error" and the description
there how that can lead to a crash when using mysql-connector-ooo.oxt:  "'rm -rf
instdir/*/share/extensions/mysql-connector-ooo', 'instdir/*/program/soffice
workdir/*/Extension/mysql-connector.oxt', install the [extension] per-user, then
'File - New - Database - Connect to an existing database: MySQL - Next >> -
Connect directly - Next >> - Database name: foo - Server / Port - Server: bar -
Next >> - Test Connection', crash."

This is a partial revert of cd79d514 "prefix all
component_getFactory methods."

Change-Id: Ia7a6272eb0597e3b3bbf4ab333174b3232448539

mysqlc/source/mysqlc.component

@@ -7,7 +7,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  *
 -->
-<component xmlns="http://openoffice.org/2010/uno-components" prefix="mysqlc"
+<component xmlns="http://openoffice.org/2010/uno-components"
         loader="com.sun.star.loader.SharedLibrary">
     <implementation name="com.sun.star.comp.sdbc.mysqlc.MysqlCDriver">
         <service name="com.sun.star.sdbc.Driver"/>

mysqlc/source/mysqlc_services.cxx

@@ -76,7 +76,7 @@ struct ProviderRequest
 
 
 /* {{{ component_getFactory -I- */
-extern "C" SAL_DLLPUBLIC_EXPORT void* SAL_CALL mysqlc_component_getFactory(
+extern "C" SAL_DLLPUBLIC_EXPORT void* SAL_CALL component_getFactory(
                     const sal_Char * pImplementationName,
                     void * pServiceManager,
                     void * /* pRegistryKey */)