Use quoted, comma-separated "system" calls.

Formula/vorbis-tools.rb

@@ -11,7 +11,8 @@ class VorbisTools <Formula
   #depends_on 'ogg123' => :optional
 
   def install
-    system "./configure --disable-debug --disable-nls --disable-dependency-tracking --prefix='#{prefix}'"
+    system "./configure", "--disable-debug", "--disable-dependency-tracking",
+                          "--disable-nls", "--prefix=#{prefix}"
     # wtf?!
     inreplace 'ogg123/Makefile', '-arch ppc ppc64 i386 x86_64', '-arch i386'
     system "make install"

Formula/xmlrpc-c.rb

@@ -10,7 +10,7 @@ class XmlrpcC <Formula
     # choosing --enable-libxml2-backend to lose some weight and not statically
     # link in expat
     #NOTE seemingly it isn't possible to build dylibs with this thing
-    system "./configure --disable-debug --enable-libxml2-backend --prefix='#{prefix}'"
+    system "./configure", "--disable-debug", "--enable-libxml2-backend", "--prefix=#{prefix}"
     system "make install"
   end
 end

Formula/yajl.rb

@@ -12,7 +12,7 @@ class Yajl <Formula
   def install
     ENV.deparallelize
 
-    system "./configure --prefix '#{prefix}'"
+    system "./configure", "--prefix#{prefix}"
     system "make install"
   end
 end