wolfssl: Use pkg-config to check for wolfSSL

The other checks trigger an automatic install of the old and incompatible
Ubuntu package on LGTM.

configure.ac

@@ -1143,11 +1143,9 @@ if test x$openssl = xtrue; then
 fi
 
 if test x$wolfssl = xtrue; then
-	wolfssl_lib=wolfssl
-	AC_CHECK_LIB([$wolfssl_lib],[wolfSSL_Init],[LIBS="$LIBS"],
-		[AC_MSG_ERROR([wolfSSL lib$wolfssl_lib not found])],[$DLLIB])
-	AC_SUBST(WOLFSSL_LIB, [-l$wolfssl_lib])
-	AC_CHECK_HEADER([wolfssl/options.h],,[AC_MSG_ERROR([wolfSSL header wolfssl/options.h not found!])])
+	PKG_CHECK_MODULES(wolfssl, [wolfssl])
+	AC_SUBST(wolfssl_CFLAGS)
+	AC_SUBST(wolfssl_LIBS)
 fi
 
 if test x$gcrypt = xtrue; then

src/libstrongswan/plugins/wolfssl/Makefile.am

@@ -2,7 +2,8 @@ AM_CPPFLAGS = \
 	-I$(top_srcdir)/src/libstrongswan
 
 AM_CFLAGS = \
-	$(PLUGIN_CFLAGS)
+	$(PLUGIN_CFLAGS) \
+	$(wolfssl_CFLAGS)
 
 if MONOLITHIC
 noinst_LTLIBRARIES = libstrongswan-wolfssl.la
@@ -32,4 +33,4 @@ libstrongswan_wolfssl_la_SOURCES = \
 
 
 libstrongswan_wolfssl_la_LDFLAGS = -module -avoid-version
-libstrongswan_wolfssl_la_LIBADD  = $(WOLFSSL_LIB)
+libstrongswan_wolfssl_la_LIBADD  = $(wolfssl_LIBS)