#45 Makefile patch fixing various build related issues

[Timo Gurr]

Attached is a patch from Gentoo:
https://gitweb.gentoo.org/repo/gentoo.git/tree/sys-apps/hdparm/files/hdparm-9.51-build.patch

• drop hardcoded -O2 flag from CFLAGS
• drop hardcoded -s (strip) flag from LDFLAGS, and respect user LDFLAGS
• fix hardcoded make and hardcoded -j2 flags
• respect CFLAGS when linking

It fixes various build related issues which Distributions unnecessarily have to work around downstream.