C front-end: support inline (and its variants) after asm

GCC supports volatile, inline, goto as asm-qualifiers:
https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html.

Author: tautschnig

regression/ansi-c/asm2/main.c

@@ -3,10 +3,11 @@
 int main()
 {
   int x, y;
-  #ifdef __GNUC__
+#ifdef __GNUC__
   asm goto ("jc %l[error];"
       : : "r"(x), "r"(&y) : "memory" : error);
-  #endif
+  asm __inline volatile("jc %l[error];" : : "r"(x), "r"(&y) : "memory" : error);
+#endif
 error:
   return 0;
 }

src/ansi-c/parser.y

@@ -2675,10 +2675,9 @@ cprover_exception_statement:
 
 volatile_or_goto_opt:
           /* nothing */
-        | TOK_VOLATILE
-        | TOK_GOTO
-        | TOK_GOTO TOK_VOLATILE
-        | TOK_VOLATILE TOK_GOTO
+        | volatile_or_goto_opt TOK_VOLATILE
+        | volatile_or_goto_opt TOK_GOTO
+        | volatile_or_goto_opt TOK_INLINE
         ;
 
 /* asm ( assembler template

src/ansi-c/scanner.l

@@ -1639,6 +1639,9 @@ __decltype          { if(PARSER.cpp98 &&
 "__volatile"    { yyless(0); BEGIN(GRAMMAR); loc(); return TOK_GCC_ASM_PAREN; }
 "__volatile__"  { yyless(0); BEGIN(GRAMMAR); loc(); return TOK_GCC_ASM_PAREN; }
 "goto"          { yyless(0); BEGIN(GRAMMAR); loc(); return TOK_GCC_ASM_PAREN; }
+"inline"        { yyless(0); BEGIN(GRAMMAR); loc(); return TOK_GCC_ASM_PAREN; }
+"__inline"      { yyless(0); BEGIN(GRAMMAR); loc(); return TOK_GCC_ASM_PAREN; }
+"__inline__"    { yyless(0); BEGIN(GRAMMAR); loc(); return TOK_GCC_ASM_PAREN; }
 .               { yyless(0); BEGIN(GRAMMAR); loc(); PARSER.asm_block_following=true; return TOK_GCC_ASM; }
 }