Remove the odd __cplusplus gating of libpki's include guards

libpki is a new, C++-only target, so I think we can assume that C files
will never include them. I forget what build mishap originally motivated
this, but it seems to have been fixed, based on a recent test run.

Change-Id: I1a7ed962a80400b29e37230ff420d0c35e2b7d52
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/85907
Auto-Submit: David Benjamin <davidben@google.com>
Reviewed-by: Rudolf Polzer <rpolzer@google.com>
Commit-Queue: Rudolf Polzer <rpolzer@google.com>

include/openssl/pki/certificate.h

diff --git a/include/openssl/pki/certificate.h b/include/openssl/pki/certificate.h
index 7c217f3..94017a1 100644
--- a/include/openssl/pki/certificate.h
+++ b/include/openssl/pki/certificate.h
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#if !defined(OPENSSL_HEADER_BSSL_PKI_CERTIFICATE_H_) && defined(__cplusplus)
+#ifndef OPENSSL_HEADER_BSSL_PKI_CERTIFICATE_H_
 #define OPENSSL_HEADER_BSSL_PKI_CERTIFICATE_H_
 
 #include <memory>
@@ -80,4 +80,4 @@
 
 BSSL_NAMESPACE_END
 
-#endif  // OPENSSL_HEADER_BSSL_PKI_CERTIFICATE_H_ && __cplusplus
+#endif  // OPENSSL_HEADER_BSSL_PKI_CERTIFICATE_H_

include/openssl/pki/ocsp.h

diff --git a/include/openssl/pki/ocsp.h b/include/openssl/pki/ocsp.h
index e3f55f9..29f529b 100644
--- a/include/openssl/pki/ocsp.h
+++ b/include/openssl/pki/ocsp.h
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#if !defined(OPENSSL_HEADER_BSSL_PKI_OCSP_H_)  && defined(__cplusplus)
+#ifndef OPENSSL_HEADER_BSSL_PKI_OCSP_H_
 #define OPENSSL_HEADER_BSSL_PKI_OCSP_H_
 
 #include <openssl/base.h>   // IWYU pragma: export
@@ -120,4 +120,4 @@
 
 BSSL_NAMESPACE_END
 
-#endif  // OPENSSL_HEADER_BSSL_PKI_OCSP_H_ && __cplusplus
+#endif  // OPENSSL_HEADER_BSSL_PKI_OCSP_H_

include/openssl/pki/signature_verify_cache.h

diff --git a/include/openssl/pki/signature_verify_cache.h b/include/openssl/pki/signature_verify_cache.h
index 1bc49ec..32cc107 100644
--- a/include/openssl/pki/signature_verify_cache.h
+++ b/include/openssl/pki/signature_verify_cache.h
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#if !defined(BSSL_PKI_SIGNATURE_VERIFY_CACHE_H_) && defined(__cplusplus)
+#ifndef BSSL_PKI_SIGNATURE_VERIFY_CACHE_H_
 #define BSSL_PKI_SIGNATURE_VERIFY_CACHE_H_
 
 #include <openssl/base.h>   // IWYU pragma: export
@@ -48,4 +48,4 @@
 
 BSSL_NAMESPACE_END
 
-#endif  // BSSL_PKI_SIGNATURE_VERIFY_CACHE_H_ && __cplusplus
+#endif  // BSSL_PKI_SIGNATURE_VERIFY_CACHE_H_

include/openssl/pki/verify_error.h

diff --git a/include/openssl/pki/verify_error.h b/include/openssl/pki/verify_error.h
index a01864d..d930371 100644
--- a/include/openssl/pki/verify_error.h
+++ b/include/openssl/pki/verify_error.h
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#if !defined(OPENSSL_HEADER_BSSL_PKI_VERIFY_ERROR_H_) && defined(__cplusplus)
+#ifndef OPENSSL_HEADER_BSSL_PKI_VERIFY_ERROR_H_
 #define OPENSSL_HEADER_BSSL_PKI_VERIFY_ERROR_H_
 
 #include <openssl/base.h>   // IWYU pragma: export