Revert "CI: Build VTest with clang"

The issue with VTest not building properly in gcc is fixed since commit
vtest/VTest@0730540c43. Revert the patch to keep
the CI configuration simple.

This reverts commit e61f53eb44.

.github/workflows/vtest.yml

@@ -63,7 +63,7 @@ jobs:
         curl -fsSL https://github.com/vtest/VTest/archive/master.tar.gz -o VTest.tar.gz
         mkdir VTest
         tar xvf VTest.tar.gz -C VTest --strip-components=1
-        make -C VTest -j$(nproc) FLAGS="-O2 -s -Wall" CC=clang
+        make -C VTest -j$(nproc) FLAGS="-O2 -s -Wall"
         sudo install -m755 VTest/vtest /usr/local/bin/vtest
     - name: Install SSL ${{ matrix.ssl }}
       if: ${{ matrix.ssl && matrix.ssl != 'stock' }}

.travis.yml

@@ -40,7 +40,7 @@ matrix:
 install:
   - git clone https://github.com/VTest/VTest.git ../vtest
   # Special flags due to: https://github.com/vtest/VTest/issues/12
-  - make -C ../vtest FLAGS="-O2 -s -Wall" CC=clang
+  - make -C ../vtest FLAGS="-O2 -s -Wall"
 
 script:
   - make -j$(nproc) ERR=1 TARGET=linux-glibc CC=$CC DEBUG=-DDEBUG_STRICT=1 $FLAGS