Changes necessary for shared library linking to succeed.

diff --git a/src/Makefile.in b/src/Makefile.in
index 9534473..12411bf 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -73,7 +73,7 @@ LTCOMPILE = $(LIBTOOL) --mode=compile --tag=CC $(CC) $(DEFS) \
 	$(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) \
 	$(AM_CFLAGS) $(CFLAGS)
 CCLD = $(CC)
-LINK = $(LIBTOOL) --mode=link --tag=CC $(CCLD) $(AM_CFLAGS) $(CFLAGS) \
+LINK = HDF4_USE_SHLIB=yes $(LIBTOOL) --mode=link --tag=CC $(CCLD) $(AM_CFLAGS) $(CFLAGS) \
 	$(AM_LDFLAGS) $(LDFLAGS) -o $@
 SOURCES = $(libhdfeos_la_SOURCES)
 DIST_SOURCES = $(libhdfeos_la_SOURCES)
@@ -125,8 +125,6 @@ INSTALL_PROGRAM = @INSTALL_PROGRAM@
 INSTALL_SCRIPT = @INSTALL_SCRIPT@
 INSTALL_STRIP_PROGRAM = @INSTALL_STRIP_PROGRAM@
 
-# Set LDFLAGS to alow the HDF-EOS library to use extern variables from HDF4
-LDFLAGS = -Wl,-single_module
 LIBOBJS = @LIBOBJS@
 LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@

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<div class='path'>path: <a href='/guix/log/?id=2beca97d010f0fff36fbad360c1f3db35eb1d66f'>root</a>/<a href='/guix/log/tests?id=2beca97d010f0fff36fbad360c1f3db35eb1d66f'>tests</a>/<a href='/guix/log/tests/rsa.key?id=2beca97d010f0fff36fbad360c1f3db35eb1d66f'>rsa.key</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/rsa.key?id=2beca97d010f0fff36fbad360c1f3db35eb1d66f&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-05-04 09:56:12 +0200'>2020-05-04</span></td><td><a href='/guix/commit/tests/rsa.key?id=43408e304ffb1149f35cb539b40d673d567c9116'>Add (guix openpgp).</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/openpgp.scm, tests/openpgp.scm, tests/civodul.key,
tests/dsa.key, tests/ed25519.key, tests/rsa.key,
tests/ed25519.sec: New files.
* Makefile.am (MODULES): Add guix/openpgp.scm.
(SCM_TESTS): Add tests/openpgp.scm.
(EXTRA_DIST): Add tests/*.key and tests/ed25519.sec.
</span></span></td><td>Ludovic Courtès</td></tr>