Only move shared libraries to /lib if they exists

In several Makemodule.am, there is a install-exec-hook-<library>
target whose role is to move the shared library from /usr/lib to /lib,
while keeping a symbolic link /usr/lib/libuuid.so ->
../../lib/<library>.so.<version>.

However, when util-linux is built with --enable-static
--disable-shared (as is needed on noMMU platforms that don't support
shared libraries), no <library>.so is built, but the
install-exec-hook-libuuid creates an invalid /usr/lib/<library>.so
symbolic link, pointing to ../../lib (yes, the directory). This causes
troubles later one when other libraries/programs are compiled with
-l<library>, as gcc thinks a shared library is available because
there's a file named /usr/lib/<library>.so.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Index: b/libuuid/src/Makemodule.am
===================================================================
--- a/libuuid/src/Makemodule.am
+++ b/libuuid/src/Makemodule.am
@@ -44,7 +44,7 @@
 
 # move lib from $(usrlib_execdir) to $(libdir) if needed
 install-exec-hook-libuuid:
-	if test "$(usrlib_execdir)" != "$(libdir)"; then \
+	if test "$(usrlib_execdir)" != "$(libdir)" -a -f "$(DESTDIR)$(usrlib_execdir)/libuuid.so"; then \
 		mkdir -p $(DESTDIR)$(libdir); \
 		mv $(DESTDIR)$(usrlib_execdir)/libuuid.so.* $(DESTDIR)$(libdir); \
 		so_img_name=$$(readlink $(DESTDIR)$(usrlib_execdir)/libuuid.so); \
Index: b/libmount/src/Makemodule.am
===================================================================
--- a/libmount/src/Makemodule.am
+++ b/libmount/src/Makemodule.am
@@ -123,7 +123,7 @@
 
 # move lib from $(usrlib_execdir) to $(libdir) if needed
 install-exec-hook-libmount:
-	if test "$(usrlib_execdir)" != "$(libdir)"; then \
+	if test "$(usrlib_execdir)" != "$(libdir)" -a -f "$(DESTDIR)$(usrlib_execdir)/libmount.so"; then \
 		mkdir -p $(DESTDIR)$(libdir); \
 		mv $(DESTDIR)$(usrlib_execdir)/libmount.so.* $(DESTDIR)$(libdir); \
 		so_img_name=$$(readlink $(DESTDIR)$(usrlib_execdir)/libmount.so); \
Index: b/libblkid/src/Makemodule.am
===================================================================
--- a/libblkid/src/Makemodule.am
+++ b/libblkid/src/Makemodule.am
@@ -220,7 +220,7 @@
 
 # move lib from $(usrlib_execdir) to $(libdir) if needed
 install-exec-hook-libblkid:
-	if test "$(usrlib_execdir)" != "$(libdir)"; then \
+	if test "$(usrlib_execdir)" != "$(libdir)" -a -f "$(DESTDIR)$(usrlib_execdir)/libblkid.so"; then \
 		mkdir -p $(DESTDIR)$(libdir); \
 		mv $(DESTDIR)$(usrlib_execdir)/libblkid.so.* $(DESTDIR)$(libdir); \
 		so_img_name=$$(readlink $(DESTDIR)$(usrlib_execdir)/libblkid.so); \