Check the PROJECT_NAME more thoroughly

This was missed in 3e1a223

Task-number: QTBUG-127953
Pick-to: 6.8
Change-Id: I2ff6cafe852ec2696aea37e2e79e3c8b95c0e8ca
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
(cherry picked from commit b8b6382)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/plugins/sqldrivers/CMakeLists.txt

@@ -78,6 +78,6 @@ if(QT_FEATURE_sql_mimer)
     add_subdirectory(mimer)
 endif()
 
-if(NOT CMAKE_PROJECT_NAME STREQUAL "QtBase" AND NOT CMAKE_PROJECT_NAME STREQUAL "Qt")
+if(NOT PROJECT_NAME STREQUAL "QtBase" AND NOT PROJECT_NAME STREQUAL "Qt")
     qt_build_repo_end()
 endif()