While the rule may really need all of the generated header files to
exist, only one of them (per genrule task) needs to be in the dependency
list, since the rest are essentially aliases.
This brings an AOSP aosp_arm-userdebug out/soong/build.ninja file from
372MB to 156MB, with equivalent functionality. The Android-aosp_arm.mk
file is reduced from 11MB to 6.5MB.
Bug: 73745773
Test: diff out/soong/build.ninja
Test: diff out/soong/Android-aosp_arm.mk
Test: rm -rf out; m
Change-Id: If17377666292cc20957417fc4c3cd52f98971d0c