mesa: android: Remove unnecessary dependency tracking rules

mesa: android: Remove unnecessary dependency tracking rules

The current AOSP master build system breaks building mesa due to the
following error:

external/mesa3d/src/compiler/Android.glsl.gen.mk:94: error:
  writing to readonly directory: "external/mesa3d/src/compiler/glsl/ir.h"

This error is bogus -- nothing "writes" to ir.h -- but the rule is
unnecessary because the generated header that is a dependency of the
non-generated header should be added to LOCAL_GENERATED_SOURCES and this
will track if the dependency needs to be regenerated.

(This change fixes a similar problem affecting nir.h too.)

Cc: Rob Clark <robdclark@chromium.org>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Amit Pundir <amit.pundir@linaro.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Alistair Strachan <astrachan@google.com>
Cc: Greg Hartman <ghartman@google.com>
Cc: Tapani Pälli <tapani.palli@intel.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Alistair Strachan <astrachan@google.com>
[jstultz: Forward ported and tweaked commit subject]
Signed-off-by: John Stultz <john.stultz@linaro.org>