[C-libcurl] Fix build error when the request operation has more than 1 parameter

Created by: ityuhui

If a request operation defined in OpenAPI spec has more than 1 parameter, the generated C-libcurl client code will lose a "+", this will cause building error.

e.g.

api/AppsV1API.c:2073:47: error: invalid suffix "strlen" on integer constant
     long sizeOfPathParams_name = strlen(name)+3strlen(namespace)+3 + strlen("{ name }");

The root cause is the template code does not handle the case that more than 1 parameters.
After I added below code:

{{#hasMore}} + {{/hasMore}}

The new generated code

long sizeOfPathParams_name = strlen(name)+3 + strlen(namespace)+3 + strlen("{ name }");

will succeed to build.

PR checklist

• Read the contribution guidelines.
• If contributing template-only or documentation-only changes which will change sample output, build the project before.
• Run the shell script(s) under ./bin/ (or Windows batch scripts under.\bin\windows) to update Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit, and these must match the expectations made by your contribution. You only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the code or mustache templates for a language ({LANG}) (e.g. php, ruby, python, etc).
• File the PR against the master: master, 4.3.x, 5.0.x. Default: master.
• Copy the technical committee to review the pull request if your PR is targeting a particular programming language.

@wing328 @zhemant