Bug 1841935 - Disable -fsanitize=function for C files. r=decoder

Clang has recently added support for function UB sanitizing for C, but
it catches cases in e.g. NSS and SQLite that are IMHO a gray area rather
than a clear case of UB (https://reviews.llvm.org/D148827#4422709).

Differential Revision: https://phabricator.services.mozilla.com/D182859

build/sanitizers/ubsan_function_blacklist.txt

@@ -0,0 +1,4 @@
+[function]
+# Disable function sanitizer for all C files (new feature in clang 17) until we
+# we can narrow this down. See bug 1841935.
+src:*.c