clang failed to compile lib/csu on Ubiquiti EdgeRouter Lite

[sig6247]

11.0-CURRENT r277126

===> lib/csu/mips (obj,depend,all,install)
rm -f .depend
CC='cc  ' mkdep -f .depend -a    -I/usr/src/lib/csu/mips/../common -I/usr/src/lib/csu/mips/../../libc/include -std=gnu99   /usr/src/lib/csu/mips/crt1.c /usr/src/lib/csu/mips/crti.S /usr/src/lib/csu/mips/crtn.S
cc  -O -pipe -G0   -I/usr/src/lib/csu/mips/../common  -I/usr/src/lib/csu/mips/../../libc/include -std=gnu99 -Wsystem-headers -Werror -Wall -Wno-format-y2k -W -Wno-unused-parameter -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow -Wunused-parameter -Wcast-align -Wchar-subscripts -Winline -Wnested-externs -Wredundant-decls -Wold-style-definition -Wno-pointer-sign -Wthread-safety -Wno-empty-body -Wno-string-plus-int -Wno-unused-const-variable -Qunused-arguments -S -o crt1.s /usr/src/lib/csu/mips/crt1.c
sed -i "" -e '/\.note\.tag/s/progbits/note/' crt1.s
cc   -c -o crt1.o crt1.s
cc  -O -pipe -G0   -I/usr/src/lib/csu/mips/../common  -I/usr/src/lib/csu/mips/../../libc/include -std=gnu99 -Wsystem-headers -Werror -Wall -Wno-format-y2k -W -Wno-unused-parameter -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wshadow -Wunused-parameter -Wcast-align -Wchar-subscripts -Winline -Wnested-externs -Wredundant-decls -Wold-style-definition -Wno-pointer-sign -Wthread-safety -Wno-empty-body -Wno-string-plus-int -Wno-unused-const-variable -Qunused-arguments  -c /usr/src/lib/csu/mips/crti.S
/usr/src/lib/csu/mips/crti.S:9:16: error: unexpected token in '.set'
 .set noreorder
               ^
/usr/src/lib/csu/mips/crti.S:13:2: error: invalid instruction mnemonic 'ptr_addu'
 PTR_ADDU sp, sp, -CALLFRAME_SIZ
 ^~~~~~~~
/usr/src/lib/csu/mips/crti.S:14:25: error: unexpected token in memory operand
 REG_S ra, CALLFRAME_RA(sp)
                        ^
/usr/src/lib/csu/mips/crti.S:26:14: error: unexpected token in '.set'
 .set reorder
             ^
/usr/src/lib/csu/mips/crti.S:33:16: error: unexpected token in '.set'
 .set noreorder
               ^
/usr/src/lib/csu/mips/crti.S:37:2: error: invalid instruction mnemonic 'ptr_addu'
 PTR_ADDU sp, sp, -CALLFRAME_SIZ
 ^~~~~~~~
/usr/src/lib/csu/mips/crti.S:38:25: error: unexpected token in memory operand
 REG_S ra, CALLFRAME_RA(sp)
                        ^
/usr/src/lib/csu/mips/crti.S:50:14: error: unexpected token in '.set'
 .set reorder
             ^
*** Error code 1

Stop.
make[4]: stopped in /usr/src/lib/csu/mips
*** Error code 1

Stop.
make[3]: stopped in /usr/src
*** Error code 1

Stop.
make[2]: stopped in /usr/src
*** Error code 1

Stop.
make[1]: stopped in /usr/src
*** Error code 1

Stop.
make: stopped in /usr/src