[db] Use custom LIKE operator adapted from sqlite's icu.c (closes #1390)

Improves the search, e.g.:
- 'é' LIKE 'e'
- 'æ' LIKE 'Æ'
- 'Ö' LIKE 'o'

sqlext/Makefile.am

@@ -2,8 +2,8 @@ pkglib_LTLIBRARIES = owntone-sqlext.la
 
 owntone_sqlext_la_SOURCES = sqlext.c
 owntone_sqlext_la_LDFLAGS = -avoid-version -module -shared
-AM_CPPFLAGS += \
-	$(COMMON_CPPFLAGS)
-
 owntone_sqlext_la_LIBADD = \
 	$(COMMON_LIBS)
+
+AM_CPPFLAGS += \
+	$(COMMON_CPPFLAGS)