Restrict usable flex version to 2.6 and higher

Don't take sub-minor versions into account

Author: albert-github

CMakeLists.txt

@@ -107,8 +107,8 @@ endif ()
 find_program(DOT NAMES dot)
 find_package(PythonInterp REQUIRED)
 find_package(FLEX REQUIRED)
-if (FLEX_VERSION VERSION_LESS 2.6.4)
-  message(SEND_ERROR "Doxygen requires at least flex version 2.6.4 (installed: ${FLEX_VERSION})")
+if (FLEX_VERSION VERSION_LESS 2.6)
+  message(SEND_ERROR "Doxygen requires at least flex version 2.6 (installed: ${FLEX_VERSION})")
 endif()
 find_package(BISON REQUIRED)
 if (BISON_VERSION VERSION_LESS 2.7)