CMake: remove TEST_glibc

Commit aa82d295c8 changed from using
minimum-linux.S to qlibraryinfo.cpp, so we no longer need this. Saves
350 ms of CMake time.

Change-Id: Ifbf974a4d10745b099b1fffd177754aa5a4096ac
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

src/corelib/configure.cmake

@@ -239,21 +239,6 @@ char buf[32];
 }
 ")
 
-# glibc
-qt_config_compile_test(glibc
-    LABEL "GNU libc"
-    CODE
-"#include <stdlib.h>
-
-int main(void)
-{
-    /* BEGIN TEST: */
-return __GLIBC__;
-    /* END TEST: */
-    return 0;
-}
-")
-
 # inotify
 qt_config_compile_test(inotify
     LABEL "inotify"
@@ -576,11 +561,6 @@ qt_feature("glib" PUBLIC PRIVATE
     CONDITION GLIB2_FOUND
 )
 qt_feature_definition("glib" "QT_NO_GLIB" NEGATE VALUE "1")
-qt_feature("glibc" PRIVATE
-    LABEL "GNU libc"
-    AUTODETECT ( LINUX OR HURD )
-    CONDITION TEST_glibc
-)
 qt_feature("icu" PRIVATE
     LABEL "ICU"
     AUTODETECT NOT WIN32

src/corelib/global/minimum-linux_p.h

@@ -43,11 +43,9 @@ QT_BEGIN_NAMESPACE
  * - statx                      4.11                    QT_CONFIG(statx)
  */
 
-#if QT_CONFIG(statx) && !QT_CONFIG(glibc)
+#if QT_CONFIG(statx) && defined(__GLIBC__)
 // if using glibc, the statx() function in sysdeps/unix/sysv/linux/statx.c
 // falls back to stat() for us.
-// (Using QT_CONFIG(glibc) instead of __GLIBC__ because the macros aren't
-// defined in assembler mode)
 #  define QT_ELF_NOTE_OS_MAJOR      4
 #  define QT_ELF_NOTE_OS_MINOR      11
 #  define QT_ELF_NOTE_OS_PATCH      0