download libxml2 instead of bundle it to meet size limit of bioc

src/Makevars.win

@@ -12,3 +12,12 @@ libxmllibs=-L$(RWINLIB)/lib${R_ARCH} -lxml2 -llzma -liconv -lz
 
 PKG_LIBS += $(LAPACK_LIBS) $(BLAS_LIBS) $(FLIBS) $(libxmllibs) `${R_HOME}/bin/Rscript -e "cytolib:::cytolib_LdFlags();cat(' ');RProtoBufLib:::LdFlags();cat(' ');RcppParallel::RcppParallelLibs()"` ${RHDF5_LIBS} -lws2_32
 
+all: clean winlibs
+
+clean:
+	rm -f $(OBJECTS) $(SHLIB)
+
+winlibs:
+	"${R_HOME}/bin${R_ARCH_BIN}/Rscript.exe" "../tools/winlibs.R" $(VERSION)
+
+.PHONY: all winlibs clean

tools/winlibs.R

@@ -0,0 +1,9 @@
+# Build against static libraries from rwinlib
+VERSION <- commandArgs(TRUE)
+if(!file.exists(sprintf("../windows/libxml2-%s/include/libxml2/libxml/parser.h", VERSION))){
+  if(getRversion() < "3.3.0") setInternet2()
+  download.file(sprintf("https://github.com/rwinlib/libxml2/archive/v%s.zip", VERSION), "lib.zip", quiet = TRUE)
+  dir.create("../windows", showWarnings = FALSE)
+  unzip("lib.zip", exdir = "../windows")
+  unlink("lib.zip")
+}