Add pkg-config-0.28 source archive.

Will be required on OS X.
diff --git a/archive/pkg-config-0.28.tar.gz b/archive/pkg-config-0.28.tar.gz
new file mode 100644
index 0000000..681681a
--- /dev/null
+++ b/archive/pkg-config-0.28.tar.gz
Binary files differ
diff --git a/scripts/build-defaults.shi b/scripts/build-defaults.shi
index 6ccecb4..ab5fdb8 100644
--- a/scripts/build-defaults.shi
+++ b/scripts/build-defaults.shi
@@ -8,6 +8,7 @@
 libiconv-1.14.tar.gz \
 libpng-1.6.12.tar.xz \
 pixman-0.32.4.tar.gz \
+pkg-config-0.28.tar.gz \
 SDL-1.2.15.tar.gz \
 zlib-1.2.8.tar.gz \
 "