Revised dependency check script.

- Removed GMP, MPFR and MPC dependencies since GCC build script will download & utilize appropriate versions of these libraries.
- Removed freetype dependency. It seems to have no reason for the host system to have this library as a must.
- Make special checks on OS X for readline & libtool to ensure that we have GNU version, not BSD implementation shipped with OS X.

depends/check-dependencies.sh

@@ -28,6 +28,19 @@ function check_header
     missing_depends+=($1); return 1
 }
 
+function check_header_nosys
+{
+    for place in ${header_paths[@]}; do
+        if [ "${place:0:12}" != "/usr/include" ]; then
+            for name in ${@:2}; do
+                [ -f "$place/$name" ] && return 0
+            done
+        fi
+    done
+
+    missing_depends+=($1); return 1
+}
+
 function check_program
 {
     binary=${2:-$1}
@@ -49,17 +62,14 @@ function check_aclocal
 
 
 
-check_header    gmp             gmp.h
-check_header    mpc             mpc.h
-check_header    mpfr            mpfr.h
+# check_header    gmp             gmp.h
+# check_header    mpc             mpc.h
+# check_header    mpfr            mpfr.h
 check_header    libelf          elf.h libelf.h libelf/libelf.h gelf.h libelf/gelf.h
 check_header    libusb          usb.h
 check_header    ncurses         ncurses.h ncurses/ncurses.h
-check_header    readline        readline.h readline/readline.h
 check_header    zlib            zlib.h
 
-
-
 check_program   git
 check_program   svn
 check_program   wget
@@ -70,14 +80,13 @@ check_program   unzip
 check_program   autoconf
 check_program   automake
 check_program   automake-1.9    # This particular version is needed too
-check_program   libtool
 check_program   cmake
 check_program   make
 check_program   gcc
 check_program   g++
 
 check_program   sdl-config
-check_program   freetype-config
+# check_program   freetype-config
 
 check_program   bison
 check_program   flex
@@ -86,7 +95,21 @@ check_program   tclsh
 check_program   makeinfo
 check_program   doxygen
 
-
+# Sometimes things will be a little different on Mac OS X...
+if [ "$(uname)" == "Darwin" ]; then
+    # readline should be checked carefully on OS X to save us from being
+    # fooled by BSD libedit.
+    brew --version 1>/dev/null 2>&1 \
+        && header_paths+=("`brew --prefix`/opt/readline/include")
+    check_header_nosys readline     readline.h readline/readline.h
+
+    # GNU libtool will be prepended with letter 'g' to prevent conflicts with
+    # the one comes along with OS X.
+    check_program      glibtool
+else
+    check_header       readline     readline.h readline/readline.h
+    check_program      libtool
+fi
 
 if [ ${#missing_depends[@]} -ne 0 ]; then
     echo "Couldn't find dependencies:"