bug#19245: Compile warnings after updating to 2.4.4

[Michael Wobst]

After I updated our project's embedded libldtl to 2.4.4, several "No 
such file or directory" compile warnings showed up; see below:

                                                               ^
mv -f .deps/libltdlc_la-lt_error.Tpo .deps/libltdlc_la-lt_error.Plo
/bin/bash ../libtool --silent  --tag=CC   --mode=compile gcc -std=gnu99 
-DHAVE_CONFIG_H -I. -I..  -DLTDLOPEN=libltdlc -DLT_CONFIG_H='<config.h>' 
-DLTDL -I. -I. -Ilibltdl -I./libltdl -Ilibltdl -I./libltdl/libltdl   -g 
-O2 -fstack-protector -fno-strict-aliasing -Wall -Wbad-function-cast 
-Wcast-align -Wcast-qual -Wclobbered -Wempty-body -Wignored-qualifiers 
-Wlogical-op -Wmissing-declarations -Wmissing-field-initializers 
-Wmissing-include-dirs -Wmissing-parameter-type -Wmissing-prototypes 
-Wnested-externs -Wold-style-declaration -Woverride-init -Wpointer-arith 
-Wredundant-decls -Wshadow -Wsign-compare -Wtype-limits -Wundef 
-Wuninitialized -Wwrite-strings -MT libltdlc_la-ltdl.lo -MD -MP -MF 
.deps/libltdlc_la-ltdl.Tpo -c -o libltdlc_la-ltdl.lo `test -f 'ltdl.c' 
|| echo './'`ltdl.c
cc1: warning: ./libltdl/libltdl: No such file or directory [enabled by 
default]

Regards,
Michael