ci: Don't apply asm goto hacks when using LLVM 9 and above

We want to test LLVM 8 in CI because it is the current release version
and we want to clearly see if there is a kernel regression or LLVM
regression. If LLVM 8 is fine but LLVM 9 causes errors, it's probably
something on the LLVM side rather than kernel.

The folder structure will now be:

llvm-all / llvm-version ->
    kernel-all / ${REPO} ->
        arch-all / ${ARCH}

Hopefully we never have to use the all folders :)

I have hesistantly added symlinks to llvm-6 and llvm-7 on the off chance
that others want to test older versions (for example, Ubuntu Bionic, the
latest LTS, has clang-6 in its repos), even though they really should be
using a newer version.

Closes: #167
Closes: #171
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

driver.sh

@@ -256,9 +256,14 @@ build_linux() {
 
   git show -s | cat
 
-  apply_patches "../patches/all"
-  apply_patches "../patches/${REPO}/all"
-  apply_patches "../patches/${REPO}/${ARCH}"
+  llvm_all_folder="../patches/llvm-all"
+  apply_patches "${llvm_all_folder}/kernel-all"
+  apply_patches "${llvm_all_folder}/${REPO}/arch-all"
+  apply_patches "${llvm_all_folder}/${REPO}/${ARCH}"
+  llvm_version_folder="../patches/llvm-$(echo __clang_major__ | ${CC} -E -x c - | tail -n 1)"
+  apply_patches "${llvm_version_folder}/kernel-all"
+  apply_patches "${llvm_version_folder}/${REPO}/arch-all"
+  apply_patches "${llvm_version_folder}/${REPO}/${ARCH}"
 
   # Only clean up old artifacts if requested, the Linux build system
   # is good about figuring out what needs to be rebuilt

patches/llvm-6

@@ -0,0 +1 @@
+llvm-8

patches/llvm-7

@@ -0,0 +1 @@
+llvm-8