Speculatively fix failing build bots

This should address the issues found by:
https://lab.llvm.org/buildbot#builders/174/builds/8451
https://lab.llvm.org/buildbot#builders/100/builds/14839
diff --git a/MultiSource/Benchmarks/Prolangs-C/bison/CMakeLists.txt b/MultiSource/Benchmarks/Prolangs-C/bison/CMakeLists.txt
index b1d447e..1f820c9 100644
--- a/MultiSource/Benchmarks/Prolangs-C/bison/CMakeLists.txt
+++ b/MultiSource/Benchmarks/Prolangs-C/bison/CMakeLists.txt
@@ -1,3 +1,4 @@
+list(APPEND CPPFLAGS -Wno-implicit-function-declaration)
 set(RUN_OPTIONS parse.y.in -v)
 llvm_multisource(mybison)
 llvm_test_data(mybison parse.y.in)
diff --git a/SingleSource/Regression/C/gcc-c-torture/execute/ieee/CMakeLists.txt b/SingleSource/Regression/C/gcc-c-torture/execute/ieee/CMakeLists.txt
index f761f85..bdbd7b8 100644
--- a/SingleSource/Regression/C/gcc-c-torture/execute/ieee/CMakeLists.txt
+++ b/SingleSource/Regression/C/gcc-c-torture/execute/ieee/CMakeLists.txt
@@ -1,6 +1,5 @@
 # GCC C Torture Suite is conventionally run without warnings
-list(APPEND CFLAGS "-w")
-
+list(APPEND CFLAGS -Wno-implicit-function-declaration -w)
 set(TestsToSkip)
 
 ##