This was preventing several things from working properly,
like Errno_pm.PL, which tried to use $Config{cppstdin},
which was not set properly.
c=''
castflags='0'
cat='type'
-cc='~CC~'
+cc='~cc~'
cccdlflags=' '
ccdlflags=' '
ccflags='-DWIN32'
contains='grep'
cp='copy'
cpio=''
-cpp='~CC~ -nologo -E'
+cpp='~cc~ -nologo -E'
cpp_stuff='42'
cppccsymbols=''
cppflags='-DWIN32'
cpplast=''
cppminus=''
-cpprun='~CC~ -nologo -E'
-cppstdin='~CC~ -nologo -E'
+cpprun='~cc~ -nologo -E'
+cppstdin='~cc~ -nologo -E'
cppsymbols=''
crosscompile='undef'
crypt_r_proto='0'