openblas: add pthreads dependency

missing since mxe#958

fixes mxe#1384

src/openblas.mk

@@ -8,7 +8,7 @@ $(PKG)_CHECKSUM := 73c40ace5978282224e5e122a41c8388c5a19e65a6f2329c2b7c0b61bacc9
 $(PKG)_SUBDIR   := OpenBLAS-$($(PKG)_VERSION)
 $(PKG)_FILE     := $($(PKG)_SUBDIR).tar.gz
 $(PKG)_URL      := http://github.com/xianyi/OpenBLAS/archive/v$($(PKG)_VERSION).tar.gz
-$(PKG)_DEPS     := gcc
+$(PKG)_DEPS     := gcc pthreads
 
 define $(PKG)_UPDATE
     $(WGET) -q -O- 'https://github.com/xianyi/OpenBLAS/releases' | \