Fail to build `LIBS` on macOS 10.7

[catap]

Local root 42b54861f26253a2ab2c71bcfbe74ee2418db293 which is failed as:

(0/8) BUILDING cfg_if from cfg-if v0.1.10
> /opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_lang_mrustc/mrustc/work/mrustc-42b54861f26253a2ab2c71bcfbe74ee2418db293/bin/mrustc rustc-1.54.0-src/vendor/cfg-if-0.1.10/src/lib.rs -o output-1.54.0/libcfg_if-0_1_10.rlib --crate-name cfg_if --crate-type rlib -C emit-depfile=output-1.54.0/libcfg_if-0_1_10.rlib.d --crate-tag 0_1_10 --cfg debug_assertions -O -L output-1.54.0 --edition 2018
Assertion failed: (t == ":"), function load_depfile, file build.cpp, line 817.
make: *** [output-1.54.0/libpanic_unwind.rlib] Abort trap: 6

The full log is available here: https://build.macports.org/builders/ports-10.7_x86_64-builder/builds/108738/steps/install-port/logs/stdio