Makefile: Install PSA headers
When running `make install`, it can be desirable for the PSA Crypto header
files to get installed as well, so that the PSA portions of the library are
usable.
diff --git a/Makefile b/Makefile
index f4c0a00..f32641a 100644
--- a/Makefile
+++ b/Makefile
@@ -24,6 +24,8 @@
install: no_test
mkdir -p $(DESTDIR)/include/mbedtls
cp -rp include/mbedtls $(DESTDIR)/include
+ mkdir -p $(DESTDIR)/include/psa
+ cp -rp include/psa $(DESTDIR)/include
mkdir -p $(DESTDIR)/lib
cp -RP library/libmbedtls.* $(DESTDIR)/lib
