Android doesn't compile, can't find stl libs

It's an issue I had with an empty project, building it with Qt 5.12.1 and the latest Android NDK r19b as well as with r18b and r15.

When I try to compile it I got this message:

clang++.exe:-1: error: error: no such file or directory: 'C:\sdks\android-ndk-r19b/sources/cxx-stl/llvm-libc++/libs//libc++.so.16

And by watching the qmake.conf of the mkspecs of Qt 5.12.1, I see on the line for the path to the stl lib directory that it misses the platform targeted (such as armeabi-v7a or x86) because the android ndk has 4 directories inside libs before libc++.so

ANDROID_SOURCES_CXX_STL_LIBDIR = $$NDK_ROOT/sources/cxx-stl/llvm-libc++/libs/$$

Both Qt 5.12.1 and ndk install dir are unchanged.