otf2bdf: handle ft2build.h to fix Linux build

Author: samford

Formula/o/otf2bdf.rb

@@ -35,6 +35,11 @@ class Otf2bdf < Formula
 
   def install
     chmod 0755, "mkinstalldirs"
+
+    # `otf2bdf.c` uses `#include <ft2build.h>`, not `<freetype2/ft2build.h>`,
+    # so freetype2 must be put into the search path.
+    ENV.append "CFLAGS", "-I#{Formula["freetype"].opt_include}/freetype2"
+
     system "./configure", "--mandir=#{man}", *std_configure_args
     system "make", "install"
   end