The qtbase/src/3rdparty/libjpeg/src/jmorecfg.h header conditionally creates a typedef for boolean (see around line 242). If HAVE_BOOLEAN is not defined, it typedefs it to int. The Android NDK (I'm using 21.3.6528147 if it matters) creates the same typedef but to the type uint8_t. This causes a typedef redefinition error. If I hack that file locally to avoid the redefinition, the build does succeed.