tests: Add '--duplicate-sources' to libgem5 SST build

Unfortunately the building of SST (in "ext/sst") depends on generated
header files. Therefore it adds the build directory to the include path.
For this to work the libgem5.so must be build with
"--duplicate-sources".

Change-Id: I5ed26a89c81402d421f5dfa110de7cf758f28694
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/70497
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

ext/sst/INSTALL.md

diff --git a/ext/sst/INSTALL.md b/ext/sst/INSTALL.md
index 1034d7d..91f92eb 100644
--- a/ext/sst/INSTALL.md
+++ b/ext/sst/INSTALL.md
@@ -61,9 +61,12 @@
 At the root of gem5 folder,
 
 ```sh
-scons build/RISCV/libgem5_opt.so -j $(nproc) --without-tcmalloc
+scons build/RISCV/libgem5_opt.so -j $(nproc) --without-tcmalloc --duplicate-sources
 ```
 
+**Note:** `--without-tcmalloc` is required to avoid a conflict with SST's malloc.
+`--duplicate-sources` is required as the compilation of SST depends on sources to be present in the "build" directory.
+
 ### Compiling the SST integration
 
 At the root of gem5 folder,

tests/nightly.sh

diff --git a/tests/nightly.sh b/tests/nightly.sh
index f5f9295..9286c54 100755
--- a/tests/nightly.sh
+++ b/tests/nightly.sh
@@ -159,7 +159,7 @@
         "${gem5_root}" --rm  --memory="${docker_mem_limit}" \
         gcr.io/gem5-test/sst-env:${tag} bash -c "\
 scons build/${isa}/libgem5_${variant}.so -j${compile_threads} \
---without-tcmalloc --ignore-style && \
+--without-tcmalloc --duplicate-sources --ignore-style && \
 cd ext/sst && \
 make clean; make -j ${compile_threads} && \
 sst --add-lib-path=./ sst/example.py && \