Remove defaults for CC and AR

AR defaults to "ar" anyway in GNU make and instead of gcc it is probably a
better idea to use just cc. The latter allows to build on freebsd 10 without
overriding CC or doing symlink tricks (because it uses clang as cc, provides
multiple gcc packages but only versioned binaries without any actual "gcc"
command name in the path).

Corresponding to flashrom svn r1865.
Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>

Makefile

@@ -29,7 +29,6 @@ PROGRAM = flashrom
 #
 # Note for anyone editing this Makefile: gnumake will happily ignore any
 # changes in this Makefile to variables set on the command line.
-CC      ?= gcc
 STRIP   ?= strip
 INSTALL = install
 DIFF    = diff
@@ -37,7 +36,6 @@ PREFIX  ?= /usr/local
 MANDIR  ?= $(PREFIX)/share/man
 CFLAGS  ?= -Os -Wall -Wshadow
 EXPORTDIR ?= .
-AR      ?= ar
 RANLIB  ?= ranlib
 LIBS_BASE ?= ..