Fix building & repro on local source (#4594)

* Fix building & repro on local source

With this
https://google.github.io/oss-fuzz/advanced-topics/reproducing/#reproduce-using-local-source-checkout
actually works

* Update Dockerfile

Co-authored-by: Abhishek Arya <inferno@chromium.org>

projects/quickjs/Dockerfile

@@ -17,6 +17,6 @@
 FROM gcr.io/oss-fuzz-base/base-builder
 RUN apt-get update && apt-get install -y make
 RUN git clone --depth 1 https://github.com/bellard/quickjs quickjs
-WORKDIR $SRC/
+WORKDIR $SRC/quickjs
 COPY build.sh $SRC/
 COPY fuzz*.c $SRC/

projects/quickjs/build.sh

@@ -16,7 +16,6 @@
 ################################################################################
 
 # build quickjs
-cd quickjs
 # Makefile should not override CFLAGS
 sed -i -e 's/CFLAGS=/CFLAGS+=/' Makefile
 CONFIG_CLANG=y make libquickjs.a