Another round of gcc/g++ fixes.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@20819 e7fa87d3-cd2b-0410-9028-fcbf551c1848

glslang/MachineIndependent/preprocessor/scanner.h

@@ -87,6 +87,9 @@ NVIDIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "parser.h"
 
 // Not really atom table stuff but needed first...
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 typedef struct SourceLoc_Rec {
     unsigned short file, line;
@@ -114,5 +117,10 @@ void SetStringNumber(int);
 void IncLineNumber(void);
 void DecLineNumber(void);
 int FreeScanner(void);                  // Free the cpp scanner
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif // !(defined(__SCANNER_H)