Merge bitcoin#480: Enable benchmark building by default

7a78f60 Print whether we're building benchmarks (Pieter Wuille)
4afec9f Build benchmarks by default (Pieter Wuille)

Pull request description:

  Building benchmarks is fast, and I have on more than one occasion forgotten to pass `--enable-benchmark`, resulting in accidentally benchmarking a former build.

  Build them by default.

Tree-SHA512: ce9096e42d9c19b63644f6b7ae153e92f9a37c3727f380329dfa332ce22a5e43151f1525979bd3516dd12f568e5e389b0acda2c383fca0e80c3cadc1d9b1d55a

configure.ac

@@ -85,9 +85,9 @@ AC_COMPILE_IFELSE([AC_LANG_SOURCE([[char foo;]])],
     ])
 
 AC_ARG_ENABLE(benchmark,
-    AS_HELP_STRING([--enable-benchmark],[compile benchmark (default is no)]),
+    AS_HELP_STRING([--enable-benchmark],[compile benchmark (default is yes)]),
     [use_benchmark=$enableval],
-    [use_benchmark=no])
+    [use_benchmark=yes])
 
 AC_ARG_ENABLE(coverage,
     AS_HELP_STRING([--enable-coverage],[enable compiler flags to support kcov coverage analysis]),
@@ -447,6 +447,7 @@ AC_MSG_NOTICE([Using field implementation: $set_field])
 AC_MSG_NOTICE([Using bignum implementation: $set_bignum])
 AC_MSG_NOTICE([Using scalar implementation: $set_scalar])
 AC_MSG_NOTICE([Using endomorphism optimizations: $use_endomorphism])
+AC_MSG_NOTICE([Building benchmarks: $use_benchmark])
 AC_MSG_NOTICE([Building for coverage analysis: $enable_coverage])
 AC_MSG_NOTICE([Building ECDH module: $enable_module_ecdh])
 AC_MSG_NOTICE([Building ECDSA pubkey recovery module: $enable_module_recovery])

src/gen_context.c

@@ -41,7 +41,7 @@ int main(int argc, char **argv) {
 
     fprintf(fp, "#ifndef _SECP256K1_ECMULT_STATIC_CONTEXT_\n");
     fprintf(fp, "#define _SECP256K1_ECMULT_STATIC_CONTEXT_\n");
-    fprintf(fp, "#include \"group.h\"\n");
+    fprintf(fp, "#include \"src/group.h\"\n");
     fprintf(fp, "#define SC SECP256K1_GE_STORAGE_CONST\n");
     fprintf(fp, "static const secp256k1_ge_storage secp256k1_ecmult_static_context[64][16] = {\n");