Fix bogus %name-prefix option syntax in all our Bison files.

%name-prefix doesn't use an "=" sign according to the Bison docs, but it
silently accepted one anyway, until Bison 3.0.  This was originally a
typo of mine in commit 012abebab1, and we
seem to have slavishly copied the error into all the other grammar files.

Per report from Vik Fearing; analysis by Peter Eisentraut.

Back-patch to all active branches, since somebody might try to build
a back branch with up-to-date tools.

contrib/cube/cubeparse.y

@@ -39,7 +39,7 @@ static NDBOX * write_point_as_box(char *s, int dim);
 /* BISON Declarations */
 %parse-param {NDBOX **result}
 %expect 0
-%name-prefix="cube_yy"
+%name-prefix "cube_yy"
 
 %token CUBEFLOAT O_PAREN C_PAREN O_BRACKET C_BRACKET COMMA
 %start box

contrib/seg/segparse.y

@@ -42,7 +42,7 @@
 /* BISON Declarations */
 %parse-param {SEG *result}
 %expect 0
-%name-prefix="seg_yy"
+%name-prefix "seg_yy"
 
 %union {
   struct BND {

src/backend/bootstrap/bootparse.y

@@ -93,7 +93,7 @@ int num_columns_read = 0;
 %}
 
 %expect 0
-%name-prefix="boot_yy"
+%name-prefix "boot_yy"
 
 %union
 {

src/backend/parser/gram.y

@@ -140,7 +140,7 @@ static TypeName *TableFuncTypeName(List *columns);
 %}
 
 %expect 0
-%name-prefix="base_yy"
+%name-prefix "base_yy"
 %locations
 
 %union

src/interfaces/ecpg/preproc/ecpg.header

@@ -376,7 +376,7 @@ add_typedef(char *name, char * dimension, char * length, enum ECPGttype type_enu
 %}
 
 %expect 0
-%name-prefix="base_yy"
+%name-prefix "base_yy"
 %locations
 
 %union {

src/pl/plpgsql/src/gram.y

@@ -74,7 +74,7 @@ static List				*read_raise_options(void);
 %}
 
 %expect 0
-%name-prefix="plpgsql_yy"
+%name-prefix "plpgsql_yy"
 
 %union {
 		int32					ival;