configure.ac: move enable-gallium-llvm dependency with-gallium-drivers

... to where it's applicable.

Since we effectively made --enable-gallium-llvm mean --enable-llvm with
earlier commits, we need to move the requirement to guard the compnents
added for the LLVM draw.

Otherwise we'll error (as below) when building RADV w/o gallium drivers.

configure: error: --enable-gallium-llvm is required when building radv

v2: Don't remove but move the dependency (Tobias).

Cc: Dave Airlie <airlied@redhat.com>
Cc: "17.0" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Tobias Droste <tdroste@gmx.de>
(cherry picked from commit 5869a7db75a144ae898dafe9d9b7cb9d6ae29e12)
diff --git a/configure.ac b/configure.ac
index 3e1e3f0..0c0f521 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1747,9 +1747,6 @@
     [enable_gallium_llvm="$enableval"],
     [enable_gallium_llvm=auto])
 
-if test -z "$with_gallium_drivers"; then
-    enable_gallium_llvm=no
-fi
 if test "x$enable_gallium_llvm" = xauto; then
     case "$host_cpu" in
     i*86|x86_64|amd64) enable_gallium_llvm=yes;;
@@ -2394,7 +2391,7 @@
     done
 fi
 
-if test "x$enable_gallium_llvm" == "xyes"; then
+if test "x$enable_gallium_llvm" == "xyes" -a "$with_gallium_drivers"; then
     llvm_require_version $LLVM_REQUIRED_GALLIUM "gallium"
     llvm_add_default_components "gallium"
 fi