Create libeasycsv_string library

Signed-off-by: Pradana AUMARS <paumars@courrier.dev>

src/Makefile.am

@@ -1,10 +1,12 @@
-lib_LTLIBRARIES = libeasycsv.la
+lib_LTLIBRARIES = libeasycsv.la libeasycsv_string.la
 libeasycsv_la_SOURCES = \
 	easycsv.c \
 	easycsv_error.h \
 	easycsv_error.c \
 	easycsv_p.h \
-	easycsv_p.c \
+	easycsv_p.c
+libeasycsv_la_LIBADD = libeasycsv_string.la
+libeasycsv_string_la_SOURCES = \
 	easycsv_string.h \
 	easycsv_string.c
 include_HEADERS = ../include/easycsv.h