tests: Stop testing libclang 4.0

Author: kulp

.github/workflows/bindgen.yml

@@ -99,7 +99,7 @@ jobs:
           - debian: null
             cross: null
             rust: null
-        llvm_version: ["4.0", "5.0", "9.0"]
+        llvm_version: ["5.0", "9.0"]
         main_tests: [1]
         release_build: [0, 1]
         no_default_features: [0, 1]
@@ -109,14 +109,6 @@ jobs:
         feature_extra_asserts: [0]
         feature_testing_only_docs: [0]
 
-        exclude:
-          # 4.0 is too old to support regular dynamic linking, so this
-          # is not expected to work.
-          - os: ubuntu-latest
-            llvm_version: "4.0"
-            no_default_features: 1
-            feature_runtime: 0
-
         include:
           # Test with extra asserts + docs just with latest llvm versions to
           # prevent explosion

appveyor.yml

@@ -2,18 +2,12 @@ environment:
   RUST_BACKTRACE: 1
   RUST_CHANNEL: "%Configuration%"
   matrix:
-  - TARGET: gnu
-    LLVM_VERSION: 4.0.0-1
-    BINDGEN_FEATURES: testing_only_libclang_4
   - TARGET: gnu
     LLVM_VERSION: 5.0.0-1
     BINDGEN_FEATURES: testing_only_libclang_5
   - TARGET: gnu
     LLVM_VERSION: 9.0.0-1
     BINDGEN_FEATURES: testing_only_libclang_9
-  - TARGET: msvc
-    LLVM_VERSION: 4.0.0
-    BINDGEN_FEATURES: testing_only_libclang_4
   - TARGET: msvc
     LLVM_VERSION: 5.0.0
     BINDGEN_FEATURES: testing_only_libclang_5