Clang-11 sanitizer seems to be broken.

It terminates with the following error message:

```
==2028==ERROR: UndefinedBehaviorSanitizer failed to allocate 0x0 (0) bytes of SetAlternateSignalStack (error code: 22)
==2028==Process memory map follows:
[memory map]
==2028==End of process memory map.
==2028==Sanitizer CHECK failed: /build/llvm-toolchain-11-mnvtwk/llvm-toolchain-11-11.1.0/compiler-rt/lib/sanitizer_common/sanitizer_common.cpp:54 ((0 && "unable to mmap")) != (0) (0, 0)
```

Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>

Author: sjaeckel

.github/workflows/main.yml

@@ -117,7 +117,7 @@ jobs:
           - { BUILDOPTIONS: '--with-cc=clang --cflags=-DMP_USE_MEMOPS --with-m64 --limit-valgrind',                              SANITIZER: '1', COMPILE_DEBUG: '0', COMPILE_LTO: '0', CONV_WARNINGS: 'strict',  OTHERDEPS: 'clang llvm' }
           - { BUILDOPTIONS: '--with-cc=clang --c89 --with-m64 --limit-valgrind',                                                 SANITIZER: '1', COMPILE_DEBUG: '0', COMPILE_LTO: '0', CONV_WARNINGS: 'strict',  OTHERDEPS: 'clang llvm' }
           - { BUILDOPTIONS: '--with-cc=clang --with-m64 --limit-valgrind --cflags=-DMP_PREC=MP_MIN_PREC',                        SANITIZER: '1', COMPILE_DEBUG: '0', COMPILE_LTO: '0', CONV_WARNINGS: '',        OTHERDEPS: 'clang llvm' }
-          - { BUILDOPTIONS: '--with-cc=clang-11 --with-m64 --limit-valgrind',                                                    SANITIZER: '1', COMPILE_DEBUG: '0', COMPILE_LTO: '0', CONV_WARNINGS: '',        OTHERDEPS: 'clang-11 llvm-11' }
+          # - { BUILDOPTIONS: '--with-cc=clang-11 --with-m64 --limit-valgrind',                                                    SANITIZER: '1', COMPILE_DEBUG: '0', COMPILE_LTO: '0', CONV_WARNINGS: '',        OTHERDEPS: 'clang-11 llvm-11' }
           - { BUILDOPTIONS: '--with-cc=clang-12 --with-m64 --limit-valgrind',                                                    SANITIZER: '1', COMPILE_DEBUG: '0', COMPILE_LTO: '0', CONV_WARNINGS: '',        OTHERDEPS: 'clang-12 llvm-12' }
           - { BUILDOPTIONS: '--with-cc=clang-13 --with-m64 --limit-valgrind',                                                    SANITIZER: '1', COMPILE_DEBUG: '0', COMPILE_LTO: '0', CONV_WARNINGS: '',        OTHERDEPS: 'clang-13 llvm-13' }
           - { BUILDOPTIONS: '--with-cc=clang-15 --with-m64 --limit-valgrind',                                                    SANITIZER: '1', COMPILE_DEBUG: '0', COMPILE_LTO: '0', CONV_WARNINGS: '',        OTHERDEPS: 'clang-15 llvm-15' }