PHPC-2166: Add -Wstrict-prototypes dev build flag and fix decl (#1382)

Author: jmikola

config.m4

@@ -73,6 +73,7 @@ if test "$PHP_MONGODB" != "no"; then
     AX_CHECK_COMPILE_FLAG(-Wno-unused-parameter,            _MAINTAINER_CFLAGS="$_MAINTAINER_CFLAGS -Wno-unused-parameter"          ,, -Werror)
     AX_CHECK_COMPILE_FLAG(-Wno-unused-but-set-variable,     _MAINTAINER_CFLAGS="$_MAINTAINER_CFLAGS -Wno-unused-but-set-variable"   ,, -Werror)
     AX_CHECK_COMPILE_FLAG(-Wno-missing-field-initializers,  _MAINTAINER_CFLAGS="$_MAINTAINER_CFLAGS -Wno-missing-field-initializers",, -Werror)
+    AX_CHECK_COMPILE_FLAG(-Wstrict-prototypes,              _MAINTAINER_CFLAGS="$_MAINTAINER_CFLAGS -Wstrict-prototypes"            ,, -Werror)
 
     MAINTAINER_CFLAGS="$_MAINTAINER_CFLAGS"
     STD_CFLAGS="-g -O0 -Wall"

src/phongo_client.h

@@ -21,7 +21,7 @@
 
 #include "phongo_classes.h"
 
-const char* php_phongo_crypt_shared_version();
+const char* php_phongo_crypt_shared_version(void);
 
 void phongo_manager_init(php_phongo_manager_t* manager, const char* uri_string, zval* options, zval* driverOptions);