Respect --disable-build-details in Android builds

* java/Makefile.in (BUILD_DETAILS, GEN_BUILD_DETAILS): New
variables.
(install_tmp): Tolerate failures in generation of metadata files
and prefix commands for such generation with GEN_BUILD_DETAILS.

* lisp/version.el (android-read-build-system)
(android-read-build-time): Return nil if metadata file does not
exist.

java/Makefile.in

@@ -57,7 +57,6 @@ else
 GZIP_PROG =
 endif
 
-
 # Android 4.3 and earlier require Emacs to be signed with a different
 # digital signature algorithm.
 
@@ -77,6 +76,11 @@ else
 AAPT_ASSET_ARGS =
 endif
 
+# This will be replaced by `--no-build-details' if details of the build
+# system are not to be recorded in generated packages.
+BUILD_DETAILS = @BUILD_DETAILS@
+GEN_BUILD_DETAILS := $(if $(BUILD_DETAILS),true ||,)
+
 SIGN_EMACS = -keystore $(srcdir)/emacs.keystore -storepass	\
 	emacs1 $(JARSIGNER_FLAGS)
 SIGN_EMACS_V2 = sign --v2-signing-enabled --ks			\
@@ -249,13 +253,13 @@ install_temp: $(CROSS_BINS) $(CROSS_LIBS) $(RESOURCE_FILES)	\
 	   | xargs ${GZIP_PROG} -9n ;				\
 	}
 # Produce metadata files providing build information and suchlike.
-	$(AM_V_SILENT)						\
+	-$(AM_V_SILENT) $(GEN_BUILD_DETAILS)			\
 	{ (cd $(top_srcdir)					\
 	   && git rev-parse HEAD || echo "Unknown")		\
 	   && (git rev-parse --abbrev-ref HEAD 			\
 	       || echo "Unknown") } 2> /dev/null >		\
 	  install_temp/assets/version
-	$(AM_V_SILENT)						\
+	-$(AM_V_SILENT) $(GEN_BUILD_DETAILS)			\
 	{ hostname; date +%s; } > install_temp/assets/build_info
 # Produce the file index.
 	$(AM_V_SILENT) $(libsrc)/asset-directory-tool 		\