Enable profiling options when 'pprof' tag is set (#2813)

This commit enables cpu, mem, block, and mutex profling of the FZF
executable. To support flushing the profiles at program exit it adds
util.AtExit to register "at exit" functions and mandates that util.Exit
is used instead of os.Exit to stop the program.

Co-authored-by: Junegunn Choi <junegunn.c@gmail.com>

src/core.go

@@ -3,7 +3,6 @@ package fzf
 
 import (
 	"fmt"
-	"os"
 	"time"
 	"unsafe"
 
@@ -29,6 +28,8 @@ func sbytes(data string) []byte {
 
 // Run starts fzf
 func Run(opts *Options, version string, revision string) {
+	defer util.RunAtExitFuncs()
+
 	sort := opts.Sort > 0
 	sortCriteria = opts.Criteria
 
@@ -38,7 +39,7 @@ func Run(opts *Options, version string, revision string) {
 		} else {
 			fmt.Println(version)
 		}
-		os.Exit(exitOk)
+		util.Exit(exitOk)
 	}
 
 	// Event channel
@@ -189,9 +190,9 @@ func Run(opts *Options, version string, revision string) {
 			}
 		}
 		if found {
-			os.Exit(exitOk)
+			util.Exit(exitOk)
 		}
-		os.Exit(exitNoMatch)
+		util.Exit(exitNoMatch)
 	}
 
 	// Synchronous search
@@ -270,7 +271,7 @@ func Run(opts *Options, version string, revision string) {
 					if reading {
 						reader.terminate()
 					}
-					os.Exit(value.(int))
+					util.Exit(value.(int))
 				case EvtReadNew, EvtReadFin:
 					if evt == EvtReadFin && nextCommand != nil {
 						restart(*nextCommand, nextEnviron)
@@ -372,9 +373,9 @@ func Run(opts *Options, version string, revision string) {
 										opts.Printer(val.Get(i).item.AsString(opts.Ansi))
 									}
 									if count > 0 {
-										os.Exit(exitOk)
+										util.Exit(exitOk)
 									}
-									os.Exit(exitNoMatch)
+									util.Exit(exitNoMatch)
 								}
 								determine(val.final)
 							}