Removed the extraneous and unnecessary "build" directory from the
staging path.

sky130/Makefile.in

diff --git a/sky130/Makefile.in b/sky130/Makefile.in
index 514cb47..b4375c5 100644
--- a/sky130/Makefile.in
+++ b/sky130/Makefile.in
@@ -169,7 +169,7 @@
 # although /tmp or a dedicated staging area are also fine, as long
 # as the install process can write to the path.
 
-STAGING_PATH = $(shell pwd)/build
+STAGING_PATH = $(shell pwd)
 
 SHARED_PDKS_PATH = $(datadir)/pdk