According to ElementsProject#3226, it looks like clang's LD error format has changed.
This patch adds the new format so we can parse the mocks successfully.
Apple clang version 11.0.3 (clang-1103.0.32.29)
```
checking for ANSI C header files... Undefined symbols for architecture x86_64:
"_fromwire_amount_msat", referenced from:
_fromwire_tlv_test_n1_tlv3 in ccj4zKdV.o
"_fromwire_bool", referenced from:
_fromwire_test_msg in ccj4zKdV.o
_fromwire_test_msg_option_short_id in ccj4zKdV.o
_fromwire_test_msg_option_one in ccj4zKdV.o
_fromwire_test_msg_option_two in ccj4zKdV.o
"_fromwire_test_enum", referenced from:
_fromwire_test_msg in ccj4zKdV.o
_fromwire_test_msg_option_short_id in ccj4zKdV.o
_fromwire_test_msg_option_one in ccj4zKdV.o
_fromwire_test_msg_option_two in ccj4zKdV.o
"_fromwire_tlvs", referenced from:
_fromwire_test_tlv1 in ccj4zKdV.o
_fromwire_test_tlv2 in ccj4zKdV.o
_fromwire_test_tlv3 in ccj4zKdV.o
"_fromwire_tu32", referenced from:
_fromwire_tlv_test_n2_tlv2 in ccj4zKdV.o
"_fromwire_tu64", referenced from:
_fromwire_tlv_test_n1_tlv1 in ccj4zKdV.o
_fromwire_tlv_test_n2_tlv1 in ccj4zKdV.o
"_fromwire_u16", referenced from:
_fromwire_test_features in ccj4zKdV.o
_fromwire_subtype_var_assign in ccj4zKdV.o
_fromwire_subtype_arrays in ccj4zKdV.o
_fromwire_tlv_test_n1_tlv4 in ccj4zKdV.o
_fromwire_tlv_test_n3_tlv3 in ccj4zKdV.o
_fromwire_test_msg in ccj4zKdV.o
_fromwire_test_tlv1 in ccj4zKdV.o
...
"_fromwire_u32", referenced from:
_fromwire_tlv_test_n3_tlv3 in ccj4zKdV.o
_fromwire_test_msg in ccj4zKdV.o
_fromwire_test_msg_option_short_id in ccj4zKdV.o
_fromwire_test_msg_option_one in ccj4zKdV.o
_fromwire_test_msg_option_two in ccj4zKdV.o
"_fromwire_u64", referenced from:
_fromwire_test_short_id in ccj4zKdV.o
_fromwire_tlv_test_n3_tlv3 in ccj4zKdV.o
"_fromwire_u8", referenced from:
_fromwire_subtype_var_assign in ccj4zKdV.o
_fromwire_subtype_var_len in ccj4zKdV.o
_fromwire_subtype_varlen_varsize in ccj4zKdV.o
_fromwire_tlv_test_n3_tlv3 in ccj4zKdV.o
"_fromwire_u8_array", referenced from:
_fromwire_test_features in ccj4zKdV.o
_fromwire_subtype_arrays in ccj4zKdV.o
_fromwire_tlv_test_n3_tlv3 in ccj4zKdV.o
_fromwire_test_msg in ccj4zKdV.o
_fromwire_test_msg_option_short_id in ccj4zKdV.o
_fromwire_test_msg_option_one in ccj4zKdV.o
_fromwire_test_msg_option_two in ccj4zKdV.o
...
```
Changelog-Fixed: Build for macOS Catalina / Apple clang v11.0.3 fixed