Adapt Makefile for RPM packaging

[mikhailnov]

When building an RPM via rpmbuild, we need to:

• pass system default compiler flags, example from ROSA 2023.1:

  $ rpm -E %optflags
  -O2 -fomit-frame-pointer -gdwarf-4 -Wstrict-aliasing=2 -pipe -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2 -fPIC -fstack-protector-strong --param=ssp-buffer-size=4 -m64 -mtune=generic

• pass system default linker flags
• pass directory where files should be copied to (DESTDIR)
• build an unstripped binary, RPM will strip it by itself and save debuginfo in a special way

All these changes will be usefull for any other packaging format, not only RPM.

[mikhailnov]

BSD systems may benefit from automaticaly set correct compiler

[ondrej-zary]

This would disable optimization and stripping for the manual build/install.

[mikhailnov]

Agree, -O2 should be left by default. What about stripping, is it really needed?