bugfix: add -export-dynamic to Makefile linker flags

Add -export-dynamic to Makefile linker flags so that blob handlers can
access getBlobManager() when they're loaded.

Tested: The symbols are now exported, however, blob handlers still
cannot resolve blobs::getBlobManager().
Change-Id: I025fdbd701133fc59356e3a0ed8881b2cdd0f2a0
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/Makefile.am b/Makefile.am
index 3564cf5..c0cbffb 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -15,6 +15,7 @@
 	$(LIBADD_DLOPEN) \
 	$(PHOSPHOR_LOGGING_LIBS) \
 	-lstdc++fs \
+	-export-dynamic \
 	-version-info 0:0:0 -shared
 
 libblobcmds_la_CXXFLAGS = \