diff -up qtbase-everywhere-src-5.12.1/src/gui/Qt5GuiConfigExtras.cmake.in.foo qtbase-everywhere-src-5.12.1/src/gui/Qt5GuiConfigExtras.cmake.in

--- qtbase-everywhere-src-5.12.1/src/gui/Qt5GuiConfigExtras.cmake.in.foo	2019-04-30 15:18:24.886346423 -0500

+++ qtbase-everywhere-src-5.12.1/src/gui/Qt5GuiConfigExtras.cmake.in	2019-04-30 15:19:48.303873296 -0500

@@ -66,8 +66,10 @@ unset(_GL_INCDIRS)

 # Don\'t check for existence of the "_qt5gui_OPENGL_INCLUDE_DIR" because it is

 # optional.

+if (NOT ${_qt5gui_OPENGL_INCLUDE_DIR} STREQUAL "/usr/include")

 list(APPEND Qt5Gui_INCLUDE_DIRS ${_qt5gui_OPENGL_INCLUDE_DIR})

 set_property(TARGET Qt5::Gui APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${_qt5gui_OPENGL_INCLUDE_DIR})

+endif()

 unset(_qt5gui_OPENGL_INCLUDE_DIR CACHE)