RPM: use default gobuild macro on RHEL

The default gobuild macro on RHEL now includes support for BUILDTAGS. So
we don't need to redefine it here.

`libtrust_openssl` buildtag will be set in the spec file for RHEL environments.

Signed-off-by: Lokesh Mandvekar <lsm5@fedoraproject.org>

rpm/buildah.spec

@@ -7,21 +7,16 @@
 %global debug_package   %{nil}
 %endif
 
-# RHEL's default %%gobuild macro doesn't account for the BUILDTAGS variable, so we
-# set it separately here and do not depend on RHEL's go-[s]rpm-macros package
-# until that's fixed.
-# c9s bz: https://bugzilla.redhat.com/show_bug.cgi?id=2227328
-# c8s bz: https://bugzilla.redhat.com/show_bug.cgi?id=2227331
-%if %{defined rhel}
-%define gobuild(o:) go build -buildmode pie -compiler gc -tags="rpm_crashtraceback libtrust_openssl ${BUILDTAGS:-}" -ldflags "-linkmode=external -compressdwarf=false ${LDFLAGS:-} -B 0x$(head -c20 /dev/urandom|od -An -tx1|tr -d ' \\n') -extldflags '%__global_ldflags'" -a -v -x %{?**};
-%endif
-
 %global gomodulesmode GO111MODULE=on
 
-%if 0%{defined fedora}
+%if %{defined fedora}
 %define build_with_btrfs 1
 %endif
 
+%if %{defined rhel}
+%define fips 1
+%endif
+
 %global git0 https://github.com/containers/%{name}
 
 Name: buildah
@@ -129,6 +124,10 @@ export BUILDTAGS="seccomp $(hack/systemd_tag.sh) $(hack/libsubid_tag.sh)"
 export BUILDTAGS+=" btrfs_noversion exclude_graphdriver_btrfs"
 %endif
 
+%if %{defined fips}
+export BUILDTAGS+=" libtrust_openssl"
+%endif
+
 %gobuild -o bin/%{name} ./cmd/%{name}
 %gobuild -o bin/imgtype ./tests/imgtype
 %gobuild -o bin/copy ./tests/copy