fix typo in build command

.SRCINFO

@@ -1,7 +1,7 @@
 pkgbase = abc-git
 	pkgdesc = System for Sequential Logic Synthesis and Formal Verification
 	pkgver = 1.02.r5444.806a996
-	pkgrel = 1
+	pkgrel = 2
 	url = https://people.eecs.berkeley.edu/~alanmi/abc/
 	arch = x86_64
 	arch = i686

PKGBUILD

@@ -7,7 +7,7 @@ _basever=1
 _patchlvl=02
 _gitversion=r5444.806a996
 pkgver=${_basever}.${_patchlvl}.${_gitversion}
-pkgrel=1
+pkgrel=2
 pkgdesc="System for Sequential Logic Synthesis and Formal Verification"
 url="https://people.eecs.berkeley.edu/~alanmi/abc/"
 arch=('x86_64' 'i686')
@@ -40,7 +40,7 @@ build() {
 
     # we build abc with PIC enabled, so we don't have to compile it multiple times
     # for the different targets
-    make ABC_USE_PIC=1 abc libabc.so -j$(NPROC)
+    make ABC_USE_PIC=1 abc libabc.so -j$(nproc)
 }
 
 package() {