Make sure that libdm usage always brings in pthread libraries, both in
pkgconfig and during manual build.

--- LVM2.2.02.130/libdm/libdevmapper.pc.in
+++ LVM2.2.02.130/libdm/libdevmapper.pc.in
@@ -9,4 +9,4 @@
 Cflags: -I${includedir} 
 Libs: -L${libdir} -ldevmapper
 Requires.private: @SELINUX_PC@ @UDEV_PC@
-Libs.private: -lm @RT_LIB@
+Libs.private: -lm @RT_LIB@ @PTHREAD_LIBS@
--- LVM2.2.02.130/tools/Makefile.in
+++ LVM2.2.02.130/tools/Makefile.in
@@ -90,6 +90,7 @@
   INSTALL_LVM_TARGETS += install_tools_static
   INSTALL_DMSETUP_TARGETS += install_dmsetup_static
   INSTALL_CMDLIB_TARGETS += install_cmdlib_static
+  STATIC_LIBS += @PTHREAD_LIBS@
 endif
 
 LVMLIBS = $(LVMINTERNAL_LIBS)
@@ -120,6 +121,10 @@
 
 include $(top_builddir)/make.tmpl
 
+ifeq ("@STATIC_LINK@", "yes")
+  STATIC_LIBS += @PTHREAD_LIBS@
+endif
+
 device-mapper: $(TARGETS_DM)
 
 CFLAGS_dmsetup.o += $(UDEV_CFLAGS) $(EXTRA_EXEC_CFLAGS)