fix compilation error with clang++17

ocispec/runtime_spec_schema_config_schema.h contains the following code which uses the reserved c++ keyword "class":
typedef struct {
    char *class;
    int32_t priority;
    yajl_val _residual;
    unsigned int priority_present : 1;
}

Thus the code fails to compile with clang++ 17.

Fixes containers#132 ( containers#132 )

Signed-off-by: Etienne Cordonnier <[email protected]>

src/ocispec/helpers.py

@@ -28,6 +28,9 @@
 import os
 import sys
 
+cxx_reserved_keywords = ["class", "delete", "explicit", "friend", "mutable", "new",
+                          "operator", "private", "protected", "public", "throw", "try", "virtual"]
+
 def append_separator(substr):
     '''
     Description: append only '_' at last position of subStr
@@ -45,6 +48,9 @@ def conv_to_c_style(name):
     '''
     if name is None or name == "":
         return ""
+    # replace C++ reserved keywords (the generated C headers can be included in C++ applications)
+    if name in cxx_reserved_keywords:
+        name = '_' + name
     name = name.replace('.', '_').replace('-', '_').replace('/', '_')
     substr = []
     preindex = 0