sagemathgh-41766: Fix command syntax for GCL FriCAS execution
    
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GCL 2.7.1 has built-in -eval processing in its process-some-args
function (at gcl_top.lsp line 213):
```
((string-equal x "-eval") (eval (read-from-string (pop args))))
```
The -- tells GCL to stop processing its own command-line options, so
-eval arguments are left for FriCAS's own evalInlineCode() to handle.
This is exactly how the texmacs mode already works (line 98 of the same
script). Without --, GCL's process-some-args intercepts -eval and tries
to read-from-string the argument as raw Lisp, which fails on FriCAS
system commands like )quit.

In sage, FriCAS with GCL hang on
```
sage: from sage.features.fricas import FriCAS
sage: FriCAS().is_functional()
```
See the suggestion from fricas/fricas#214


### 📝 Checklist

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- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

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URL: sagemath#41766
Reported by: Chenxin Zhong
Reviewer(s): Martin Rubey

sagemathgh-41766: Fix command syntax for GCL FriCAS execution
    
<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes sagemath#12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes sagemath#12345". -->
GCL 2.7.1 has built-in -eval processing in its process-some-args
function (at gcl_top.lsp line 213):
```
((string-equal x "-eval") (eval (read-from-string (pop args))))
```
The -- tells GCL to stop processing its own command-line options, so
-eval arguments are left for FriCAS's own evalInlineCode() to handle.
This is exactly how the texmacs mode already works (line 98 of the same
script). Without --, GCL's process-some-args intercepts -eval and tries
to read-from-string the argument as raw Lisp, which fails on FriCAS
system commands like )quit.

In sage, FriCAS with GCL hang on
```
sage: from sage.features.fricas import FriCAS
sage: FriCAS().is_functional()
```
See the suggestion from fricas/fricas#214


### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->

- [ ] The title is concise and informative.
- [ ] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
    
URL: sagemath#41766
Reported by: Chenxin Zhong
Reviewer(s): Martin Rubey

sagemathgh-41766: Fix command syntax for GCL FriCAS execution
    
<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes sagemath#12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes sagemath#12345". -->
GCL 2.7.1 has built-in -eval processing in its process-some-args
function (at gcl_top.lsp line 213):
```
((string-equal x "-eval") (eval (read-from-string (pop args))))
```
The -- tells GCL to stop processing its own command-line options, so
-eval arguments are left for FriCAS's own evalInlineCode() to handle.
This is exactly how the texmacs mode already works (line 98 of the same
script). Without --, GCL's process-some-args intercepts -eval and tries
to read-from-string the argument as raw Lisp, which fails on FriCAS
system commands like )quit.

In sage, FriCAS with GCL hang on
```
sage: from sage.features.fricas import FriCAS
sage: FriCAS().is_functional()
```
See the suggestion from fricas/fricas#214


### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->

- [ ] The title is concise and informative.
- [ ] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
    
URL: sagemath#41766
Reported by: Chenxin Zhong
Reviewer(s): Martin Rubey