Collect all lsdump paths and write them to $(OUT_DIR).

$(OUT_DIR)/target/product/$(TARGET_DEVICE)/lsdump_paths.txt will contain all
.lsdump paths relative to $(ANDROID_BUILD_TOP). This helps faster lookup while
running scripts to generate reference dumps.

Test: m -j findlsdumps for aosp_arm64_ab.
      $OUT_DIR/lsdump_paths/generic_arm64_ab/paths.txt has paths to lsdump files
      generated for the build.

Test: m -j findlsdumps for aosp_arm_ab.
      $OUT_DIR/target/product/generic_arm_ab/lsump_paths.txt has paths to
      lsdump files generated for the build.

Change-Id: Iab1640f57bf9d0af5e88e6dda64a610fedcbe87e