pkg-config can be unavailable, leading to empty PKGCFGDIR, thus 'mkdir -p' fails. fixed by checking if PKGCFGDIR is empty
diff --git a/Makefile b/Makefile
index 37a7ba9..86d1c4c 100644
--- a/Makefile
+++ b/Makefile
@@ -252,7 +252,12 @@
 LIBOBJ += $(OBJDIR)/MCInst.o
 
 
+ifeq ($(PKG_EXTRA),)
+PKGCFGDIR = $(LIBDATADIR)/pkgconfig
+else
 PKGCFGDIR ?= $(LIBDATADIR)/pkgconfig
+endif
+
 API_MAJOR=$(shell echo `grep -e CS_API_MAJOR include/capstone/capstone.h | grep -v = | awk '{print $$3}'` | awk '{print $$1}')
 VERSION_EXT =