Run tests in CI with char as unsigned char

.github/workflows/main.yml

@@ -130,3 +130,10 @@ jobs:
       - uses: actions/checkout@v2
       - name: 'Sanitizer Tests'
         run: build-scripts/test-sanitizers
+  UnsignedChar:
+    runs-on: ubuntu-latest
+    needs: Prebuild
+    steps:
+      - uses: actions/checkout@v2
+      - name: 'Unsigned Char Tests'
+        run: build-scripts/test-unsigned-char

build-scripts/test-unsigned-char

@@ -0,0 +1,18 @@
+#!/bin/bash
+set -e
+sudo apt-get update
+sudo apt-get -y install \
+   build-essential cmake \
+   zlib1g-dev libjpeg-dev libgnutls28-dev libssl-dev
+# Some platforms have unsigned-char by default, but Intel doesn't.
+# This ensures that we catch code that would fail if char were
+# unsigned by default.
+env CFLAGS="-funsigned-char" \
+    CXXFLAGS="-funsigned-char" \
+    cmake -S . -B build \
+    -DCI_MODE=1 -DBUILD_STATIC_LIBS=0 -DCMAKE_BUILD_TYPE=Release \
+    -DREQUIRE_CRYPTO_OPENSSL=1 -DREQUIRE_CRYPTO_GNUTLS=1 \
+    -DENABLE_QTC=1
+cmake --build build -j$(nproc) -- -k
+cd build
+ctest --verbose