aesni: Split plugin to avoid potential SIGILL

Because the CFLAGS applied to the whole plugin, the compiler could
"optimize" the boilerplate plugin code, which could then cause a SIGILL
on hardware that doesn't support such instructions.  This change makes
sure only the actual AES implementation is compiled like that, which
would then not get registered depending on the CPU feature detection.

src/libstrongswan/plugins/aesni/Makefile.am

@@ -2,18 +2,10 @@ AM_CPPFLAGS = \
 	-I$(top_srcdir)/src/libstrongswan
 
 AM_CFLAGS = \
-	-maes \
-	-mpclmul \
-	-mssse3 \
 	$(PLUGIN_CFLAGS)
 
-if MONOLITHIC
-noinst_LTLIBRARIES = libstrongswan-aesni.la
-else
-plugin_LTLIBRARIES = libstrongswan-aesni.la
-endif
-
-libstrongswan_aesni_la_SOURCES = \
+noinst_LTLIBRARIES = libaesni.la
+libaesni_la_SOURCES = \
 	aesni_key.h aesni_key.c \
 	aesni_cbc.h aesni_cbc.c \
 	aesni_ecb.h aesni_ecb.c \
@@ -21,7 +13,21 @@ libstrongswan_aesni_la_SOURCES = \
 	aesni_ccm.h aesni_ccm.c \
 	aesni_gcm.h aesni_gcm.c \
 	aesni_xcbc.h aesni_xcbc.c \
-	aesni_cmac.h aesni_cmac.c \
+	aesni_cmac.h aesni_cmac.c
+
+libaesni_la_CFLAGS = \
+	-maes \
+	-mpclmul \
+	-mssse3
+
+if MONOLITHIC
+noinst_LTLIBRARIES += libstrongswan-aesni.la
+else
+plugin_LTLIBRARIES = libstrongswan-aesni.la
+endif
+
+libstrongswan_aesni_la_SOURCES = \
 	aesni_plugin.h aesni_plugin.c
 
 libstrongswan_aesni_la_LDFLAGS = -module -avoid-version
+libstrongswan_aesni_la_LIBADD = libaesni.la