Tests: Extend CMake.FileDownload test internal timeouts

On a busy machine running many tests in parallel the `file(DOWNLOAD)`
step can take longer than 2 seconds even to simply copy a file.
Raise the timeout to 4 seconds to reduce spurious failures.

Tests/CMakeTests/FileDownloadTest.cmake.in

@@ -1,3 +1,5 @@
+set(timeout 4)
+
 if(NOT "@CMAKE_CURRENT_SOURCE_DIR@" MATCHES "^/")
   set(slash /)
 endif()
@@ -8,14 +10,14 @@ message(STATUS "FileDownload:1")
 file(DOWNLOAD
   ${url}
   ${dir}/file1.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   )
 
 message(STATUS "FileDownload:2")
 file(DOWNLOAD
   ${url}
   ${dir}/file2.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   SHOW_PROGRESS
   )
 
@@ -31,7 +33,7 @@ message(STATUS "FileDownload:3")
 file(DOWNLOAD
   ${url}
   ${dir}/file3.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   EXPECTED_MD5 dbd330d52f4dbd60115d4191904ded92
   )
 
@@ -39,7 +41,7 @@ message(STATUS "FileDownload:4")
 file(DOWNLOAD
   ${url}
   ${dir}/file3.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   STATUS status
   EXPECTED_HASH SHA1=67eee17f79d9ac557284fc0b8ad19f25723fb578
   )
@@ -48,7 +50,7 @@ message(STATUS "FileDownload:5")
 file(DOWNLOAD
   ${url}
   ${dir}/file3.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   STATUS status
   EXPECTED_HASH SHA224=ba283726bbb602776818b463943189afd91836cb7ee5dd6e2c7b5ae4
   )
@@ -57,7 +59,7 @@ message(STATUS "FileDownload:6")
 file(DOWNLOAD
   ${url}
   ${dir}/file3.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   STATUS status
   EXPECTED_HASH SHA256=cf3334b1275071e1da6e8c396ccb72cf1b2388d8c937526f3af26230affb9423
   )
@@ -66,7 +68,7 @@ message(STATUS "FileDownload:7")
 file(DOWNLOAD
   ${url}
   ${dir}/file3.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   STATUS status
   EXPECTED_HASH SHA384=43a5d13978d97c660db44481aee0604cb4ff6ca0775cd5c2cd68cd8000e107e507c4caf6c228941231041e282ffb8950
   )
@@ -75,7 +77,7 @@ message(STATUS "FileDownload:8")
 file(DOWNLOAD
   ${url}
   ${dir}/file3.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   STATUS status
   EXPECTED_HASH SHA512=6984e0909a1018030ccaa418e3be1654223cdccff0fe6adc745f9aea7e377f178be53b9fc7d54a6f81c2b62ef9ddcd38ba1978fedf4c5e7139baaf355eefad5b
   )
@@ -83,7 +85,7 @@ message(STATUS "FileDownload:9")
 file(DOWNLOAD
   ${url}
   ${dir}/file3.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   STATUS status
   EXPECTED_HASH MD5=dbd330d52f4dbd60115d4191904ded92
   )
@@ -92,7 +94,7 @@ message(STATUS "FileDownload:10")
 file(DOWNLOAD
   ${url}
   ${dir}/file3.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   STATUS status
   EXPECTED_MD5 dbd330d52f4dbd60115d4191904ded92
   )
@@ -102,7 +104,7 @@ message(STATUS "FileDownload:11")
 file(DOWNLOAD
   badhostname.png
   ${dir}/file11.png
-  TIMEOUT 2
+  TIMEOUT ${timeout}
   STATUS status
   )
 message(STATUS "${status}")