configure: check for -pthread vs -lpthread (#379)

Makefile

@@ -30,7 +30,7 @@ GENH = src/version.h
 CFLAGS  += -Wall -O0 -g -std=c99 -D_GNU_SOURCE -pipe
 NO_AS_NEEDED = -Wl,--no-as-needed
 LIBDL   = -ldl
-LDFLAGS = -fPIC $(NO_AS_NEEDED) $(LIBDL) -lpthread
+LDFLAGS = -fPIC $(NO_AS_NEEDED) $(LIBDL) $(PTHREAD)
 INC     = 
 PIC     = -fPIC
 AR      = $(CROSS_COMPILE)ar

configure

@@ -208,6 +208,15 @@ fi
 echo "$LD_SONAME_FLAG"
 echo "LD_SET_SONAME = -Wl,$LD_SONAME_FLAG," >> config.mak
 
+if check_link "checking whether we can use -lpthread" "-lpthread" \
+"int main(){return 0;}" ; then
+echo "PTHREAD = -lpthread" >> config.mak
+else
+check_link "checking whether we can use -pthread" "-pthread" \
+"int main(){return 0;}" || fail "no pthread support detected"
+echo "PTHREAD = -pthread" >> config.mak
+fi
+
 make_cmd=make
 if ismac ; then
 	echo LDSO_SUFFIX=dylib>>config.mak