gallium: Wrap some header files into "extern C"

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7477>

src/gallium/auxiliary/nir/nir_draw_helpers.h

@@ -25,6 +25,11 @@
 
 #ifndef NIR_DRAW_HELPERS_H
 #define NIR_DRAW_HELPERS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct nir_shader;
 void
 nir_lower_pstipple_fs(struct nir_shader *shader,
@@ -37,4 +42,9 @@ nir_lower_aaline_fs(struct nir_shader *shader, int *varying);
 
 void
 nir_lower_aapoint_fs(struct nir_shader *shader, int *varying);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif

src/gallium/auxiliary/util/u_pstipple.h

@@ -31,6 +31,10 @@
 
 #include "pipe/p_compiler.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct pipe_context;
 struct pipe_resource;
 struct pipe_shader_state;
@@ -58,5 +62,8 @@ util_pstipple_create_fragment_shader(const struct tgsi_token *tokens,
                                      unsigned fixed_unit,
                                      unsigned wincoordFile);
 
+#ifdef __cplusplus
+}
+#endif
 
 #endif