testing/sssd: fails to build, configure script is broken

configure:27321: checking for headers required to compile python extensions
configure:27330:  -Os -fomit-frame-pointer -I/usr/include/python3.9 -I/usr/include/python3.9 conftest.c
./configure: eval: line 1: -Os: not found
configure:27330: $? = 127

When I set env. variable CPP=g++:

configure:27321: checking for headers required to compile python extensions
configure:27330: g++ -Os -fomit-frame-pointer -I/usr/include/python3.9 -I/usr/include/python3.9 conftest.c
/usr/lib/gcc/x86_64-alpine-linux-musl/10.3.1/../../../../x86_64-alpine-linux-musl/bin/ld: /usr/lib/gcc/x86_64-alpine-linux-musl/10.3.1/../../../../lib/Scrt1.o: in function `_start_c':
/home/buildozer/aports/main/musl/src/v1.2.2/crt/crt1.c:18: undefined reference to `main'
collect2: error: ld returned 1 exit status
configure:27330: $? = 1

Also, it’s some ancient version (1.16.5), the latest available version is 2.6.0 (https://github.com/SSSD/sssd).