cmake: drop `if(PKG_CONFIG_FOUND)` guard for `pkg_check_modules()`

The oldest cmake supported by curl is v3.7.0, which already has such
guard (using `PKG_CONFIG_EXECUTABLE`) inside `pkg_check_modules()`. The
advantage of leaving that guard to CMake is that it will define/reset
all output variables, while the manual guard doesn't do this and also
leaves for example `NETTLE_FOUND` undefined.

Delete the single use of this guard from the recently added `nettle`
detection, where I included it by accident. Then possibly re-introduce
it universally if we find it useful after more evaluation.

Follow-up to 669ce42275635dc1f881dab3dfc9a55c9ab49b21 #14285
Closes #14309

diff --git a/CMake/FindNettle.cmake b/CMake/FindNettle.cmake
index ec6d4cbd6ed52f3e7081cb153e5b922abeb40233..96d7d6f6a6984f36fd76495acaa10c5eb0e5df17 100644 (file)
--- a/CMake/FindNettle.cmake
+++ b/CMake/FindNettle.cmake
@@ -30,9 +30,7 @@
 
 if(UNIX)
   find_package(PkgConfig QUIET)
-  if(PKG_CONFIG_FOUND)
-    pkg_check_modules(NETTLE "nettle")
-  endif()
+  pkg_check_modules(NETTLE "nettle")
 endif()
 
 if(NETTLE_FOUND)