Revert move to RHEL 8 build until issues are resolved with using devkit build

- Builds need a build ID or this to be disabled in the RPM
- Builds likely need the annobin annotations

Also, place the pkgos definition high enough that it is usable by portablesuffix.

Related: RHEL-30943

java-21-openjdk.spec

@@ -143,6 +143,11 @@
 # Set of architectures where we verify backtraces with gdb
 %global gdb_arches %{jit_arches} %{zero_arches}
 
+# Define the OS the portable JDK is built on
+# This is undefined for openjdk-portable-rhel-8 builds and
+# equals 'rhel7' for openjdk-portable-rhel-7 builds
+%global pkgos rhel7
+
 # By default, we build a debug build during main build on JIT architectures
 %if %{with slowdebug}
 %ifarch %{debug_arches}
@@ -1262,12 +1267,6 @@ Provides: java-%{origin}-src%{?1} = %{epoch}:%{version}-%{release}
 
 # Prevent brp-java-repack-jars from being run
 %global __jar_repack 0
-# Define the OS the portable JDK is built on
-# This is undefined for openjdk-portable-rhel-8 builds and
-# equals 'rhel7' for openjdk-portable-rhel-7 builds
-%if 0
-%global pkgos rhel7
-%endif
 # Define the root name of the portable packages
 %global pkgnameroot java-%{featurever}-%{origin}-portable%{?pkgos:-%{pkgos}}
 
@@ -2484,7 +2483,6 @@ require "copy_jdk_configs.lua"
 
 %changelog
 * Fri Apr 12 2024 Andrew Hughes <gnu.andrew@redhat.com> - 1:21.0.2.0.13-2
-- Disable setting pkgos to rhel7 to revert to the openjdk-portable-rhel-8 version
 - Sync the copy of the portable specfile with the latest update
 - Define portablesuffix according to whether pkgos is defined or not
 - Related: RHEL-30943