{gsm,gb}/Makefile.am: drop undefined $GCC_FVISIBILITY_HIDDEN

Change-Id: I142cf38e8954720ed66b0c242a5527c96626dcaa
diff --git a/src/gb/Makefile.am b/src/gb/Makefile.am
index b0fcaa9..f3bbcfb 100644
--- a/src/gb/Makefile.am
+++ b/src/gb/Makefile.am
@@ -4,7 +4,7 @@
 LIBVERSION=14:0:0
 
 AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_builddir)/include
-AM_CFLAGS = -Wall ${GCC_FVISIBILITY_HIDDEN} -fno-strict-aliasing \
+AM_CFLAGS = -Wall -fno-strict-aliasing \
 	    $(TALLOC_CFLAGS) \
 	    $(LIBMNL_CFLAGS) \
 	    $(NULL)
diff --git a/src/gsm/Makefile.am b/src/gsm/Makefile.am
index 7e2949e..a3820d7 100644
--- a/src/gsm/Makefile.am
+++ b/src/gsm/Makefile.am
@@ -4,7 +4,7 @@
 LIBVERSION=18:0:0
 
 AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_builddir)/include $(TALLOC_CFLAGS)
-AM_CFLAGS = -Wall ${GCC_FVISIBILITY_HIDDEN}
+AM_CFLAGS = -Wall
 
 if ENABLE_PSEUDOTALLOC
 AM_CPPFLAGS += -I$(top_srcdir)/src/pseudotalloc