removed redundant tests

clang v3.8 tests are either flacky or redundant,
prefer using clang-latest.

.github/workflows/generic-dev.yml

@@ -128,18 +128,6 @@ jobs:
         make gcc6install libc6install
         CC=gcc-6 CFLAGS="-O2 -m32" FUZZER_FLAGS="--long-tests" make uasan-fuzztest
 
-  clang-38-msan-fuzz:
-    runs-on: ubuntu-16.04 # fails on 18.04
-    steps:
-    - uses: actions/checkout@v2
-    - name: clang-3.8 + MSan + Fuzz Test
-      run: |
-        # make clang38install (doesn't work)
-        sudo apt-add-repository "deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.8 main"
-        sudo apt-get update
-        sudo apt-get install clang-3.8
-        CC=clang-3.8 make clean msan-fuzztest
-
   asan-ubsan-msan-regression:
     runs-on: ubuntu-latest
     steps:

.github/workflows/generic-release.yml

@@ -34,16 +34,13 @@ jobs:
         make -C tests test-zbuff
 
   tsan:
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
     - name: thread sanitizer
       run: |
-        sudo apt-add-repository "deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.8 main"
-        sudo apt-get update
-        sudo apt-get install clang-3.8
-        CC=clang-3.8 make tsan-test-zstream
-        CC=clang-3.8 make tsan-fuzztest
+        CC=clang make tsan-test-zstream
+        CC=clang make tsan-fuzztest
 
   zlib-wrapper:
     runs-on: ubuntu-16.04