[opam] update build instructions

opam/opam

@@ -88,10 +88,9 @@ tags: [
 
 build: [
   ["autoconf"] {dev}
-  ["./configure" "--prefix" prefix
-                 "--mandir=%{man}%"
-  ]
-  [make "-j%{jobs}%"]
+  ["./configure"]
+  [make "config.sed"]
+  ["dune" "build" "-j%{jobs}%" "--release" "@install"]
   [make "-C" "doc" "download"] {with-doc}
 ]
 
@@ -101,10 +100,10 @@ install: [
 ]
 
 run-test: [
-  [make "-j%{jobs}%" "PTESTS_OPTS=-error-code" "tests"] { arch != "ppc64" & arch != "x86_32" & arch != "arm32" }
-  # tests are disabled on PPC64 due to floating-point oracle differences
-  # (some ULPs in libc trigonometric functions) and due to the lack of
-  # available hardware to test them locally
+  ["dune" "exec" "--" "frama-c-ptests" "tests" "src/plugins/*/tests"
+  ] { arch != "ppc64" & arch != "x86_32" & arch != "arm32" }
+  ["dune" "build" "-j%{jobs}%" "@ptests_config"
+  ] { arch != "ppc64" & arch != "x86_32" & arch != "arm32" }
 ]
 
 # Please keep depends and depopts sorted by package name