Various loplugin warnings in mysql

I assume the "0 == " around columnStringValue.equalsIgnoreAsciiCase in
ODatabaseMetaData::getSchemas (mysqlc/source/mysqlc_databasemetadata.cxx) was
just a thinko, as the latter already returns sal_Bool, not a <0 / 0 / >0 integer
value.

(Rebased atop ce24919c "loplugin, various in
mysqlc", which covered the same warnings, but didn't consider the negated call
to equalsIgnoreAsciiCase to be an accident as I do here (see above), and
accidentally reversed the logic of OResultSetMetaData::isNullable in
mysqlc/source/mysqlc_resultsetmetadata.cxx, I think.)

Change-Id: Ie89cc8ef7c7638d28307a4b240930d387d75b8f2
Reviewed-on: https://gerrit.libreoffice.org/58908
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

compilerplugins/clang/check.cxx

@@ -89,7 +89,7 @@ TerminalCheck TypeCheck::AnyBoolean() const {
         n == "sal_Bool" || n == "BOOL" || n == "Boolean" || n == "FT_Bool"
         || n == "FcBool" || n == "GLboolean" || n == "NPBool" || n == "TW_BOOL"
         || n == "UBool" || n == "boolean" || n == "dbus_bool_t"
-        || n == "gboolean" || n == "hb_bool_t" || n == "jboolean");
+        || n == "gboolean" || n == "hb_bool_t" || n == "jboolean" || n == "my_bool");
 }
 
 TypeCheck TypeCheck::LvalueReference() const {

mysqlc/source/mysqlc_connection.cxx

@@ -277,7 +277,7 @@ void SAL_CALL OConnection::setAutoCommit(sal_Bool autoCommit)
 {
     MutexGuard aGuard(m_aMutex);
     checkDisposed(OConnection_BASE::rBHelper.bDisposed);
-    if(!mysql_autocommit(&m_mysql, static_cast<my_bool>(autoCommit)))
+    if(!mysql_autocommit(&m_mysql, autoCommit))
         mysqlc_sdbc_driver::throwSQLExceptionWithMsg(mysql_error(&m_mysql), mysql_errno(&m_mysql), *this, getConnectionEncoding());
 }
 

mysqlc/source/mysqlc_databasemetadata.cxx

@@ -909,7 +909,7 @@ Reference< XResultSet > SAL_CALL ODatabaseMetaData::getSchemas()
         for (sal_uInt32 i = 1; i <= columns; i++) {
             rtl::OUString columnStringValue = xRow->getString(i);
             if (i == 1) {   // TABLE_SCHEM
-                informationSchema = !columnStringValue.equalsIgnoreAsciiCase("information_schema");
+                informationSchema = columnStringValue.equalsIgnoreAsciiCase("information_schema");
             }
             aRow.push_back(makeAny(columnStringValue));
         }

mysqlc/source/mysqlc_resultsetmetadata.cxx

@@ -165,7 +165,7 @@ sal_Int32 SAL_CALL OResultSetMetaData::isNullable(sal_Int32 column)
 {
     checkColumnIndex(column);
     MYSQL_FIELD* pField = getField(column);
-    return sal_Int32((pField->flags & NOT_NULL_FLAG) != 0);
+    return (pField->flags & NOT_NULL_FLAG) ? 0 : 1;
 }
 
 sal_Bool SAL_CALL OResultSetMetaData::isSearchable(sal_Int32 /*column*/)