RFR: JDK-8243477 FreeType library check should prefer 64-bit directory

[Magnus Ihse Bursie]

The check for the system freetype library should check the 64-bit 
library first on 64-bit systems, before falling back to the generic 
"lib" directory.

When fixing this, I noticed that lib-freetype.m4 needed a lot of love, 
so I shaped it up a bit. Changes made to code quality:
  * Indentation and spacing errors fixed
  * All tests were executed in subshells, which is not necessary. The 
original author presumably did not know what the "if (test ...) " shell 
syntax means.
  * Several lines were far too long. While the file is still not 
perfect, it's much better. (And we've never been zealous about the 80 
char length limit anyway.)

The only "real" change in the file was that I moved the check for 
$OPENJDK_TARGET_CPU_BITS to be the first of the well-known location tests.

Bug: https://bugs.openjdk.java.net/browse/JDK-8243477
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8243477-fix-freetype-lib64/webrev.01

/Magnus