log support requires CGO

[miekg]

#70 and #69 add log support, but it calls a clib, so now we no longer create a static build, but ref libc and friends

This also makes a releasing a no go, because I will probably have an incompatible libc.

go bc -ldflags="-extldflags=-static"  
# github.com/virtual-kubelet/systemk
/usr/bin/ld: /tmp/go-link-075005359/000015.o: in function `_cgo_d744bec0c646_Cfunc_dlopen':
/tmp/go-build/cgo-gcc-prolog:90: warning: Using 'dlopen' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-075005359/000025.o: in function `mygetgrouplist':
/home/miek/up/go/src/os/user/getgrouplist_unix.go:16: warning: Using 'getgrouplist' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-075005359/000024.o: in function `mygetgrgid_r':
/home/miek/up/go/src/os/user/cgo_lookup_unix.go:38: warning: Using 'getgrgid_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-075005359/000024.o: in function `mygetgrnam_r':
/home/miek/up/go/src/os/user/cgo_lookup_unix.go:43: warning: Using 'getgrnam_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-075005359/000024.o: in function `mygetpwnam_r':
/home/miek/up/go/src/os/user/cgo_lookup_unix.go:33: warning: Using 'getpwnam_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-075005359/000024.o: in function `mygetpwuid_r':
/home/miek/up/go/src/os/user/cgo_lookup_unix.go:28: warning: Using 'getpwuid_r' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
/usr/bin/ld: /tmp/go-link-075005359/000020.o: in function `_cgo_26061493d47f_C2func_getaddrinfo':
/tmp/go-build/cgo-gcc-prolog:58: warning: Using 'getaddrinfo' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
****

This creates a static bin on my setup.
Another downside of cgo is that per go routines stack is no longer 2k, it's 1M or something

[miekg]

mygetgrgid_r warning (and friends) might actually cause breakage

[miekg]

it does run on debian stable

[miekg]

ok, the dyn. linked binary runs on RH8 - which is good. I'm still going to add the PR to remove this all together, but it seems this usable at this point

[pires]

For reference, the code as is in main has been validated by me in RHEL7, RHEL8 and Ubuntu 20.04.