Add required pkg-config for Dockerfile.simple
Add required pkg-config for Dockerfile.simple

This fix tries to address the issue raised in 35980 where
pkg-config was missing and was causing Dockerfile.simple build
to fail.

```
$ docker build -t docker:simple -f Dockerfile.simple .
..........
CGO_ENABLED=1 go build  -tags "seccomp apparmor selinux netgo cgo static_build" -installsuffix netgo -ldflags "-w -extldflags -static -X main.gitCommit="b2567b37d7b75eb4cf325b77297b140ea686ce8f" -X main.version=1.0.0-rc4+dev " -o runc .
pkg-config: exec: "pkg-config": executable file not found in $PATH
make: *** [static] Error 2
Makefile:42: recipe for target 'static' failed
The command '/bin/sh -c /tmp/install-binaries.sh runc containerd tini proxy dockercli' returned a non-zero code: 2
```

This fix fixes 35980.

Signed-off-by: Yong Tang <765086fe2e0c1f980161f127fec596800f327f62@outlook.com>

djs55/docker,SvenDowideit/docker,jwhonce/docker,unclejack/docker,Ramzec/docker,x1022as/docker,thaJeztah/docker,paralin/docker,KingEmet/docker,moby/moby,kolyshkin/moby,mahak/docker,thaJeztah/docker,KingEmet/docker,dccurtis/docker,scotttlin/docker,laijs/docker,scotttlin/docker,moul/docker,vdemeester/docker,jvanz/docker,mikebrow/docker,laijs/moby,rhatdan/docker,jwhonce/docker,dmcgowan/docker,dmcgowan/docker,moul/docker,nawawi/docker,nalind/docker,konstruktoid/docker-upstream,flavio/docker,jlhawn/docker,pradipd/moby,jwhonce/docker,jimjag/docker,tophj-ibm/docker,bearstech/moby,nawawi/docker,yosifkit/docker,justincormack/docker,AkihiroSuda/docker,crosbymichael/docker,justincormack/docker,johnstep/moby-moby,Mokolea/docker,laijs/moby,rremer/moby,tophj-ibm/moby,yosifkit/docker,whuwxl/docker,mahak/docker,maxamillion/docker,ripcurld0/moby,konstruktoid/docker-1,rhatdan/docker,jlhawn/docker,kojiromike/docker,justincormack/docker,laijs/moby,AkihiroSuda/docker,docker/docker,KingEmet/docker,johnstep/moby-moby,jthelin/docker,duglin/docker,docker/docker,thaJeztah/docker,dims/docker,YuPengZTE/docker,bearstech/moby,paralin/docker,mahak/docker,pradipd/moby,nawawi/docker,crosbymichael/docker,jthelin/docker,SvenDowideit/docker,tophj-ibm/docker,tonistiigi/docker,flavio/docker,SvenDowideit/docker,noironetworks/docker,tophj-ibm/moby,docker/docker,jvanz/docker,ibuildthecloud/docker,johnstep/moby-moby,jameszhan/docker,vdemeester/docker,jlhawn/docker,dims/docker,allencloud/docker,rremer/moby,rancher/docker,unclejack/docker,yongtang/docker,cpuguy83/docker,rancher/docker,rancher/docker,dims/docker,ripcurld0/moby,KarthikNayak/docker,konstruktoid/docker-upstream,thaJeztah/docker,mixja/docker,estesp/docker,ibuildthecloud/docker,konstruktoid/docker-upstream,trebonian/docker,x1022as/docker,tmp6154/docker,gnailuy/docker,laijs/docker,moul/docker,tonistiigi/docker,kolyshkin/docker,mikebrow/docker,nalind/docker,nalind/docker,jimjag/docker,moby/moby,yongtang/docker,YuPengZTE/docker,kojiromike/docker,unclejack/docker,maxamillion/docker,noironetworks/docker,yongtang/docker,noironetworks/docker,jvanz/docker,dmcgowan/docker,estesp/docker,laijs/docker,Ramzec/docker,jimjag/docker,cpuguy83/docker,kolyshkin/moby,ibuildthecloud/docker,cpuguy83/docker,ibuildthecloud/docker,jameszhan/docker,AkihiroSuda/docker,paralin/docker,trebonian/docker,x1022as/docker,KarthikNayak/docker,mikebrow/docker,ripcurld0/moby,trebonian/docker,mixja/docker,gnailuy/docker,jimjag/docker,djs55/docker,YuPengZTE/docker,paralin/docker,vdemeester/docker,tmp6154/docker,konstruktoid/docker-1,scotttlin/docker,moby/moby,nawawi/docker,dccurtis/docker,bearstech/moby,moul/docker,dccurtis/docker,nalind/docker,maxamillion/docker,crosbymichael/docker,yosifkit/docker,Ramzec/docker,flavio/docker,konstruktoid/docker-upstream,tophj-ibm/moby,rremer/moby,cpuguy83/docker,whuwxl/docker,djs55/docker,allencloud/docker,allencloud/docker,jameszhan/docker,flavio/docker,estesp/docker,moby/moby,trebonian/docker,mahak/docker,rhatdan/docker,AkihiroSuda/docker,Mokolea/docker,duglin/docker,ibuildthecloud/docker,Mokolea/docker,kolyshkin/moby,yosifkit/docker,whuwxl/docker,tonistiigi/docker,pradipd/moby,Ramzec/docker,gnailuy/docker,duglin/docker,kojiromike/docker,KarthikNayak/docker,mixja/docker,tophj-ibm/docker,kolyshkin/docker,bearstech/moby,konstruktoid/docker-1,gnailuy/docker,Mokolea/docker,tmp6154/docker