Make the makefile compatible with Busybox

Busybox follows stricter POSIX standards, and doesn't support the --mode
and --directory arguments, but rather uses the shorthand variants -m and
-d

Makefile

@@ -34,8 +34,8 @@ DESTDIR    ?= /tmp/test-mce-dev
 PCDIR      := /usr/lib/pkgconfig
 INCLUDEDIR := /usr/include/mce
 
-INSTALL_DIR  := install --mode=755 --directory
-INSTALL_DATA := install --mode=644
+INSTALL_DIR  := install -m 755 -d
+INSTALL_DATA := install -m 644
 
 
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