add configure check for working compiler
without this, broken choices of CC/CPPFLAGS/CFLAGS don't show up until
late in the configure process where they are confusingly reported as a
different failure such as incorrect long double type.
diff --git a/configure b/configure
index e8a990b..5d95672 100755
--- a/configure
+++ b/configure
@@ -189,6 +189,15 @@
printf "%s\n" "$CC"
test -n "$CC" || { echo "$0: cannot find a C compiler" ; exit 1 ; }
+printf "checking whether C compiler works... "
+echo "typedef int x;" > "$tmpc"
+if output=$($CC $CPPFLAGS $CFLAGS -c -o /dev/null "$tmpc" 2>&1) ; then
+printf "yes\n"
+else
+printf "no; compiler output follows:\n%s\n" "$output"
+exit 1
+fi
+
#
# Only build musl-gcc wrapper if toolchain does not already target musl
#