[New] `install`: add parallel build support for openbsd

Co-authored-by: Lukman <lukmaan.me@gmail.com>
Co-authored-by: Sladyn Nunes <sladynnunes98@gmail.com>

nvm.sh

@@ -1760,6 +1760,7 @@ nvm_get_os() {
     Darwin\ *) NVM_OS=darwin ;;
     SunOS\ *) NVM_OS=sunos ;;
     FreeBSD\ *) NVM_OS=freebsd ;;
+    OpenBSD\ *) NVM_OS=openbsd ;;
     AIX\ *) NVM_OS=aix ;;
   esac
   nvm_echo "${NVM_OS-}"
@@ -2160,7 +2161,7 @@ nvm_get_make_jobs() {
     "_linux")
       NVM_CPU_CORES="$(nvm_grep -c -E '^processor.+: [0-9]+' /proc/cpuinfo)"
     ;;
-    "_freebsd" | "_darwin")
+    "_freebsd" | "_darwin" | "_openbsd")
       NVM_CPU_CORES="$(sysctl -n hw.ncpu)"
     ;;
     "_sunos")