Use the name LIBCRYPTO in the auto-tools.

configure.ac

@@ -37,7 +37,7 @@ AM_CONDITIONAL(HAVE_RST2MAN, [test "x$RST2MAN" != "xno"])
 
 m4_ifndef([VARNISH_PREREQ], AC_MSG_ERROR([Need varnish.m4 -- see README.rst]))
 
-PKG_CHECK_MODULES([CRYPTO], [libcrypto])
+PKG_CHECK_MODULES([LIBCRYPTO], [libcrypto])
 
 VARNISH_PREREQ([trunk])
 VARNISH_VMODS([ece])

src/Makefile.am

 AUTOMAKE_OPTIONS = subdir-objects
 
-AM_CFLAGS = $(VARNISHAPI_CFLAGS) @CRYPTO_CFLAGS@ -Wall -Werror -Wextra -std=c99
-AM_LDFLAGS = $(VARNISHAPI_LIBS) @CRYPTO_LIBS@ -ldl
+AM_CFLAGS = $(VARNISHAPI_CFLAGS) @LIBCRYPTO_CFLAGS@ -Wall -Werror -Wextra \
+	-std=c99
+AM_LDFLAGS = $(VARNISHAPI_LIBS) @LIBCRYPTO_LIBS@ -ldl
 
 vmod_LTLIBRARIES = libvmod_ece.la