gstreamer.mk tries to do the following replacements:

ifeq ($(GSTREAMER_INCLUDE_FONTS),yes)
GSTREAMER_INCLUDE_FONTS_SUBST=""
else
GSTREAMER_INCLUDE_FONTS_SUBST="//"
endif

ifeq ($(GSTREAMER_INCLUDE_CA_CERTIFICATES),yes)
GSTREAMER_INCLUDE_CA_CERTIFICATES_SUBST=""
else
GSTREAMER_INCLUDE_CA_CERTIFICATES_SUBST="//"
endif

ifneq (,$(findstring yes,$(GSTREAMER_INCLUDE_FONTS)$(GSTREAMER_INCLUDE_CA_CERTIFICATES)))
GSTREAMER_COPY_FILE_SUBST=""
else
GSTREAMER_COPY_FILE_SUBST="//"
endif

[...]

	@"$(SED)" "s;@INCLUDE_FONTS@;$(GSTREAMER_INCLUDE_FONTS_SUBST);g" $(GSTREAMER_NDK_BUILD_PATH)/GStreamer.java | \
		"$(SED)" "s;@INCLUDE_CA_CERTIFICATES@;$(GSTREAMER_INCLUDE_CA_CERTIFICATES_SUBST);g" | \
		"$(SED)" "s;@INCLUDE_COPY_FILE@;$(GSTREAMER_COPY_FILE_SUBST);g" \
		> $(GSTREAMER_JAVA_SRC_DIR)/org/freedesktop/gstreamer/GStreamer.java

This fails because the replacement is set to one double quote character, and the double quote character ends the replacement statement prematurely.

This seems to work after modifying the statements which set the replacement values:


ifeq ($(GSTREAMER_INCLUDE_FONTS),yes)
GSTREAMER_INCLUDE_FONTS_SUBST :=
else
GSTREAMER_INCLUDE_FONTS_SUBST := //
endif

ifeq ($(GSTREAMER_INCLUDE_CA_CERTIFICATES),yes)
GSTREAMER_INCLUDE_CA_CERTIFICATES_SUBST :=
else
GSTREAMER_INCLUDE_CA_CERTIFICATES_SUBST := //
endif

ifneq (,$(findstring yes,$(GSTREAMER_INCLUDE_FONTS)$(GSTREAMER_INCLUDE_CA_CERTIFICATES)))
GSTREAMER_COPY_FILE_SUBST :=
else
GSTREAMER_COPY_FILE_SUBST := //
endif


gstreamer.mk is called by Android.mk which is part of gstreamer android tutorial-5.
To build, I call ndk-build.cmd, which is part of Android NDK.  

I downloaded gstreamer from here:
https://gstreamer.freedesktop.org/data/pkg/android/1.9.1/gstreamer-1.0-android-armv7-1.9.1.tar.bz2