Add racket package (#463)

* racket: update to 6.6

* patch for /bin/sh

disabled-packages/racket/build.sh

@@ -1,6 +1,6 @@
 TERMUX_PKG_HOMEPAGE=https://racket-lang.org
 TERMUX_PKG_DESCRIPTION="Full-spectrum programming language going beyond Lisp and Scheme"
-TERMUX_PKG_VERSION=6.4
+TERMUX_PKG_VERSION=6.6
 TERMUX_PKG_SRCURL=https://mirror.racket-lang.org/installers/${TERMUX_PKG_VERSION}/racket-minimal-${TERMUX_PKG_VERSION}-src-builtpkgs.tgz
 TERMUX_PKG_FOLDERNAME=racket-${TERMUX_PKG_VERSION}
 TERMUX_PKG_HOSTBUILD=true
@@ -12,7 +12,14 @@ TERMUX_PKG_EXTRA_CONFIGURE_ARGS="--enable-racket=$TERMUX_PKG_HOSTBUILD_DIR/racke
 _CROSS_LIBTOOL_DIR=$TERMUX_PKG_CACHEDIR/libtool-cross-2.4.6-${TERMUX_HOST_PLATFORM}
 TERMUX_PKG_EXTRA_CONFIGURE_ARGS+=" --enable-lt=$_CROSS_LIBTOOL_DIR/bin/${TERMUX_HOST_PLATFORM}-libtool"
 
-LDFLAGS+=" -llog"
+termux_step_pre_configure () {
+  LDFLAGS+=" -llog"
+}
+
+termux_step_pre_make () {
+	cd "$TERMUX_PKG_SRCDIR/.."
+	sed "s%\@TERMUX_PREFIX\@%${TERMUX_PREFIX}%g" $TERMUX_PKG_BUILDER_DIR/system.rkt.patch.special | patch -p1
+}
 
 termux_step_post_extract_package () {
 	if [ ! -d $_CROSS_LIBTOOL_DIR ]; then

disabled-packages/racket/system.rkt.patch.special

@@ -0,0 +1,13 @@
+diff -u -r a/collects/racket/system.rkt ./collects/racket/system.rkt
+index 9de72fe..78beae6 100644
+--- a/racket/collects/racket/system.rkt
++++ ./collects/racket/system.rkt
+@@ -17,7 +17,7 @@
+ 
+ (define (shell-path/args who argstr)
+   (case (system-type)
+-    [(unix macosx) (append '("/bin/sh" "-c") (list argstr))]
++    [(unix macosx) (append '("@TERMUX_PREFIX@/bin/sh" "-c") (list argstr))]
+     [(windows) (let ([cmd
+                       (let ([d (find-system-path 'sys-dir)])
+                         (let ([cmd (build-path d "cmd.exe")])