configure.ac: move AC_ARG_ENABLE([gallium-llvm] hunk further up

With next commits we'll require --enable-gallium-llvm (en route to a
greater good later on) for RADV. The latter is required to ensure that
as otherwise we'll fail to build.

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 38abcdba8a59e88a91d598951323b977fb3fa1ad)
diff --git a/configure.ac b/configure.ac
index 57fd407..d991969 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1731,6 +1731,24 @@
 fi
 
 
+dnl
+dnl Gallium LLVM
+dnl
+AC_ARG_ENABLE([gallium-llvm],
+    [AS_HELP_STRING([--enable-gallium-llvm],
+        [build gallium LLVM support @<:@default=enabled on x86/x86_64@:>@])],
+    [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;;
+    esac
+fi
+
 #
 # Vulkan driver configuration
 #
@@ -2137,24 +2155,6 @@
     GL_PC_CFLAGS="$GL_PC_CFLAGS -DMESA_EGL_NO_X11_HEADERS"
 fi
 
-dnl
-dnl Gallium LLVM
-dnl
-AC_ARG_ENABLE([gallium-llvm],
-    [AS_HELP_STRING([--enable-gallium-llvm],
-        [build gallium LLVM support @<:@default=enabled on x86/x86_64@:>@])],
-    [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;;
-    esac
-fi
-
 dnl Directory for XVMC libs
 AC_ARG_WITH([xvmc-libdir],
     [AS_HELP_STRING([--with-xvmc-libdir=DIR],