Given following log snippets, their explanation, and nothing else, explain what failure, if any, occurred during build of this package.

  Snippets are in a format of [X] : [Y], where [X] is a log snippet, and [Y] is the explanation.

  Snippets are delimited with '================'.

  Drawing on information from all snippets, provide a concise explanation of the issue and recommend a solution.

  Explanation of the issue, and recommended solution, should take a handful of sentences.

  Snippets:

  [+ CC=clang]: [clang has been selected as the default C compiler.]
=============
[+ CXX=clang++]: [clang++ has been selected as the default C++ compiler.]
=============
[gcc -O2 -flto=thin -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS --config=/usr/lib/rpm/redhat/redhat-hardened-clang.cfg -fstack-protector-strong -m64 -march=x86-64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -c -o /tmp/ffconf.iTr4BAq3/test.o /tmp/ffconf.iTr4BAq3/test.c
]: [The package is using gcc to compile a C file.]
=============
[gcc: error: unrecognized command-line option '--config=/usr/lib/rpm/redhat/redhat-hardened-clang.cfg'
]: [This is the error causing the build to fail.]

Issue: The build fails because the default C compiler for the RPM build has been set to clang, but the package source hard-codes gcc as the C compiler.  This causes the build to fail, because gcc is being passed clang compile flags which it doesn't support.
Resolution: Patch the upstream source code to respect the CC environment variable instead for hard-coding gcc.