Allow the configs parameter for eglChooseConfig to be null in shadow

[copybara-service]

Allow the configs parameter for eglChooseConfig to be null in shadow

Most of the time, the output parameters for EGL methods are
expected to be non-null. But the configs parameter of
eglChooseConfig is one of the exceptions. When configs is
not null, eglChooseConfig fills that with the first
configSize configs and fills numConfig with the number of
returned configs (no more than configsSize). But when configs
is_ null it fills numConfigs with the number of matching
configs, ignoring configsSize:
https://registry.khronos.org/EGL/sdk/docs/man/html/eglChooseConfig.xhtml

The Android code wrapping this API checks that attrib_list and
num_configs output arrays are not null, but allows configs
to be null (see frameworks/base/core/jni/android_opengl_EGL14.cpp).