Remove undesired OPENSSL_EXPORT's in non-library code

Bug: chromium:1322914

Change-Id: I2efbb110747273188245530f9ab1964faba5201c
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/62825
Reviewed-by: David Benjamin <davidben@google.com>
Auto-Submit: Bob Beck <bbe@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

pki/fillins/file_util.h

@@ -15,7 +15,7 @@ namespace bssl {
 
 namespace fillins {
 
-OPENSSL_EXPORT bool ReadFileToString(const FilePath &path, std::string *out);
+bool ReadFileToString(const FilePath &path, std::string *out);
 
 }  // namespace fillins
 

pki/fillins/path_service.h

@@ -13,7 +13,7 @@ namespace bssl {
 
 namespace fillins {
 
-class OPENSSL_EXPORT FilePath {
+class FilePath {
  public:
   FilePath();
   FilePath(const std::string &path);
@@ -30,7 +30,7 @@ enum PathKey {
   DIR_SOURCE_ROOT = 0,
 };
 
-class OPENSSL_EXPORT PathService {
+class PathService {
  public:
   static void Get(PathKey key, FilePath *out);
 };