Upgrade Emscripten + build fixes

- Upgraded to 3.1.47.
 - EM_CACHE override leads to some new issues with package search in sysroot, probably because sysroot is hardcoded in PKG_CONFIG* variables. Use Docker's path mapping mechanism instead.
 - Added temporary workaround for new issue from https://github.com/emscripten-core/emscripten/issues/16836.

Dockerfile

@@ -1,5 +1,4 @@
-FROM emscripten/emsdk:3.1.3
-RUN apt-get update && apt-get install -qqy autoconf autopoint pkg-config
+FROM emscripten/emsdk:3.1.47
+RUN apt-get update && apt-get install -qqy autoconf autopoint pkg-config libtool libtool-bin
 WORKDIR /src
-ENV EM_CACHE /src/deps/.emcache
 CMD ["sh", "-c", "emmake make -j`nproc`"]

Makefile

@@ -1,4 +1,4 @@
-SYSROOT = $(EM_CACHE)/sysroot
+SYSROOT = /emsdk/upstream/emscripten/cache/sysroot
 
 # Add custom sysroot to library & macro search paths.
 export LDFLAGS += -L$(SYSROOT)/lib
@@ -6,6 +6,8 @@ export ACLOCAL_PATH := $(SYSROOT)/share/aclocal:$(ACLOCAL_PATH)
 
 # Common linking flags for all targets.
 export LDFLAGS += -s DYNAMIC_EXECUTION=0 -s AUTO_JS_LIBRARIES=0 -s AUTO_NATIVE_LIBRARIES=0
+# Temporary workaround for https://github.com/emscripten-core/emscripten/issues/16836.
+export LDFLAGS += -Wl,-u,ntohs
 
 # Common compilation & linking flags for all langs and targets.
 COMMON_FLAGS = -Os -flto

build.sh

@@ -16,8 +16,7 @@
 # License along with this library; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 
-if [ -z "$CI" ]
-then
+if [ -z "$CI" ]; then
 	DOCKER_INTERACTIVE_OPTS="-it"
 else
 	DOCKER_INTERACTIVE_OPTS=""
@@ -26,6 +25,6 @@ fi
 docker build -t web-gphoto2 - <Dockerfile
 docker run --rm $DOCKER_INTERACTIVE_OPTS \
 	-v $PWD:/src \
-	-u $(id -u):$(id -g) \
+	-v $PWD/deps/.emcache:/emsdk/upstream/emscripten/cache \
 	web-gphoto2 \
 	$@