Merge bitcoin-core/secp256k1#1190: Make all non-API functions (except main) static

e03ef86559 Make all non-API functions (except main) static (Pieter Wuille)

Pull request description:

ACKs for top commit:
  real-or-random:
    utACK e03ef86559
  hebasto:
    ACK e03ef86559.

Tree-SHA512: 36a35d9a8da05411c88644aec81e79883febce3e08c9eb6b0ec95cfc3705fd6abfd66f7ee10dfa081ca20786d26b0a060ead7f5c8109bf02a73dde7ef811144b

src/ctime_tests.c

@@ -30,7 +30,7 @@
 #include "../include/secp256k1_schnorrsig.h"
 #endif
 
-void run_tests(secp256k1_context *ctx, unsigned char *key);
+static void run_tests(secp256k1_context *ctx, unsigned char *key);
 
 int main(void) {
     secp256k1_context* ctx;
@@ -63,7 +63,7 @@ int main(void) {
     return 0;
 }
 
-void run_tests(secp256k1_context *ctx, unsigned char *key) {
+static void run_tests(secp256k1_context *ctx, unsigned char *key) {
     secp256k1_ecdsa_signature signature;
     secp256k1_pubkey pubkey;
     size_t siglen = 74;