Automatically generate private symbol name mangling macros.

Rather than using a manually maintained list of internal symbols to
drive name mangling, add a compilation phase to automatically extract
the list of internal symbols.

This resolves #677.

include/jemalloc/internal/private_namespace.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
 
-for symbol in `cat $1` ; do
+for symbol in `cat "$@"` ; do
   echo "#define ${symbol} JEMALLOC_N(${symbol})"
 done