appimage: Strip header files out of appimage

Some header files libclang ships are quite huge (megabytes). Looks like
they're for ARM. Regardless, we don't need any header files at runtime.

This saves us about 1M of disk space.

flake.nix

@@ -159,6 +159,7 @@
               # Exclude the following groups to reduce appimage size:
               #
               # *.a: Static archives are not necessary at runtime
+              # *.h: Header files are not necessary at runtime (some ARM headers for clang are large)
               # *.pyc, *.py, *.whl: bpftrace does not use python at runtime
               # libLLVM-11.so: Appimage uses the latest llvm we support, so not llvm11
               #
@@ -172,6 +173,7 @@
               # ```
               exclude = [
                 "... *.a"
+                "... *.h"
                 "... *.pyc"
                 "... *.py"
                 "... *.whl"