Merge bitcoin-core/secp256k1#1183: Bugfix: pass SECP_CONFIG_DEFINES to bench compilation

c0a555b Bugfix: pass SECP_CONFIG_DEFINES to bench compilation (Pieter Wuille)

Pull request description:

ACKs for top commit:
  real-or-random:
    utACK c0a555b
  apoelstra:
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Tree-SHA512: 4ec6ca4c012166beb6c5bdd1b2ed939554415e03545c176cf281000145c4000a460e231d5da26f617a81b048cd0fa3f8f16b61a207aed9479fdd854483e35ded

Author: real-or-random

Makefile.am

@@ -105,6 +105,7 @@ if USE_BENCHMARK
 noinst_PROGRAMS += bench bench_internal bench_ecmult
 bench_SOURCES = src/bench.c
 bench_LDADD = libsecp256k1.la $(SECP_LIBS) $(SECP_TEST_LIBS) $(COMMON_LIB)
+bench_CPPFLAGS = $(SECP_CONFIG_DEFINES)
 bench_internal_SOURCES = src/bench_internal.c
 bench_internal_LDADD = $(SECP_LIBS) $(COMMON_LIB) $(PRECOMPUTED_LIB)
 bench_internal_CPPFLAGS = $(SECP_INCLUDES) $(SECP_CONFIG_DEFINES)