Make build_and_run.sh work from repo root

Author: maximecb

uvclang/build_and_run.sh

@@ -1,10 +1,17 @@
 #!/bin/sh
 # Compile a source file with uvclang and run the result in the UVM VM.
-# All arguments are forwarded to uvclang, so flags work as usual:
+# All arguments are forwarded to uvclang, so flags work as usual. Works from any
+# directory; input paths resolve against your current directory:
 #   ./build_and_run.sh examples/synth.c
-#   ./build_and_run.sh -O0 tests/printf.c
+#   uvclang/build_and_run.sh uvclang/tests/printf.c   # e.g. from the repo root
 set -e
-cd "$(dirname "$0")"
+
+# Resolve this script's directory so we can find the crates and write out.asm
+# here regardless of the caller's working directory. We deliberately do NOT cd:
+# staying in the caller's directory lets relative input paths resolve naturally
+# (uvclang's own include dir is compiled-in absolute, so it needs no cd).
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+
 export RUST_BACKTRACE=1
-cargo run -q -- "$@" -o out.asm
-exec cargo run -q --manifest-path ../vm/Cargo.toml -- out.asm
+cargo run -q --manifest-path "$SCRIPT_DIR/Cargo.toml" -- "$@" -o "$SCRIPT_DIR/out.asm"
+exec cargo run -q --manifest-path "$SCRIPT_DIR/../vm/Cargo.toml" -- "$SCRIPT_DIR/out.asm"