use immediate evaluation for shell calls

This reworks the shell calls in the makefiles to use immediate
evaluation and should improve parallel building.

X-Gentoo-Bug: 289264
X-Gentoo-Bug-URL: http://bugs.gentoo.org/show_bug.cgi?id=289264

mk/sys.mk

@@ -12,8 +12,8 @@ SH=			/bin/sh
 
 PREFIX?=	
 _UPREFIX_SH=		case "${PREFIX}" in "") echo /usr;; *) echo "${PREFIX}";; esac
-_UPREFIX!=		${_UPREFIX_SH}
-UPREFIX=		${_UPREFIX}$(shell ${_UPREFIX_SH})
+_UPREFIX:=		$(shell ${_UPREFIX_SH})
+UPREFIX=		${_UPREFIX}
 LOCAL_PREFIX=		/usr/local
 
 PICFLAG?=		-fPIC
@@ -30,8 +30,8 @@ INCDIR?=		${UPREFIX}/include
 INCMODE?=		0444
 
 _LIBNAME_SH=		case `readlink /lib` in /lib64|lib64) echo "lib64";; *) echo "lib";; esac
-_LIBNAME!=		${_LIBNAME_SH}
-LIBNAME?=		${_LIBNAME}$(shell ${_LIBNAME_SH})
+_LIBNAME:=		$(shell ${_LIBNAME_SH})
+LIBNAME?=		${_LIBNAME}
 LIBDIR?=		${UPREFIX}/${LIBNAME}
 LIBMODE?=		0444
 SHLIBDIR?=		${PREFIX}/${LIBNAME}