build: Makefile -> GNUmakefile
diff --git a/Makefile b/GNUmakefile
similarity index 100%
rename from Makefile
rename to GNUmakefile
diff --git a/decompressor/Makefile b/decompressor/GNUmakefile
similarity index 100%
rename from decompressor/Makefile
rename to decompressor/GNUmakefile
diff --git a/stage23/Makefile b/stage23/GNUmakefile
similarity index 100%
rename from stage23/Makefile
rename to stage23/GNUmakefile
