Glitch in CURL_VERSION_TLSAUTH_SRP autoconf probe

[fweimer-rh]

The double "" in "SRP"" introduce a syntax error, causing this probe to fail always:

https://github.com/m6w6/ext-http/blob/ff2148e3f14ab76babbabc7a759fc80fefd1e769/autoconf/pecl/libcurl.m4#L136C1-L136C90

conftest.c: In function 'main':
conftest.c:54:129: warning: missing terminating " character
   54 |                                                 int set_failure = curl_easy_setopt(curl_easy_init(), CURLOPT_TLSAUTH_TYPE, "SRP"");
      |                                                                                                                                 ^
conftest.c:57:1: error: unterminated argument list invoking macro "curl_easy_setopt"
   57 | 
      | ^
conftest.c:54:67: error: initialization of 'int' from 'CURLcode (*)(CURL *, CURLoption, ...)' {aka 'CURLcode (*)(void *, CURLoption, ...)'} makes integer from pointer without a cast
   54 |                                                 int set_failure = curl_easy_setopt(curl_easy_init(), CURLOPT_TLSAUTH_TYPE, "SRP"");
      |                                                                   ^~~~~~~~~~~~~~~~
conftest.c:54:49: error: expected ',' or ';' at end of input
   54 |                                                 int set_failure = curl_easy_setopt(curl_easy_init(), CURLOPT_TLSAUTH_TYPE, "SRP"");
      |                                                 ^~~
conftest.c:54:49: error: expected declaration or statement at end of input
conftest.c:54:53: warning: unused variable 'set_failure' [-Wunused-variable]
   54 |                                                 int set_failure = curl_easy_setopt(curl_easy_init(), CURLOPT_TLSAUTH_TYPE, "SRP"");
      |                                                     ^~~~~~~~~~~
conftest.c:53:53: warning: unused variable 'has_feature' [-Wunused-variable]
   53 |                                                 int has_feature = curl_version_info(CURLVERSION_NOW)->features & CURL_VERSION_TLSAUTH_SRP;
      |                                                     ^~~~~~~~~~~

When fixing this, please make sure that the probe, when successful, does not trigger any compiler warnings related to integer/pointer conversion or incompatible pointer types.

Found as a side effect of:

• https://fedoraproject.org/wiki/Changes/PortingToModernC
• https://fedoraproject.org/wiki/Toolchain/PortingToModernC

[m6w6]

Now, that's a catch. 🖖

[m6w6]

Fix breaks "the fix"