This is needed for example to pass an include path set in the CPPFLAGS
environment variable to the bitcode compile command.
Discussion: https://www.postgresql.org/message-id/flat/
c1384a7b-ed12-4862-a0da-
a05c7945171a%40eisentraut.org
if llvm.version().version_compare('=15.0')
bitcode_cflags += ['-Xclang', '-no-opaque-pointers']
endif
+bitcode_cflags += get_option('c_args')
bitcode_cflags += cppflags
# XXX: Worth improving on the logic to find directories here