convert: rename the "eol" global variable to "core_eol"

Yes, it is clear that "eol" wants to mean some sort of end-of-line thing,
but as the name of a global variable, it is way too short to describe what
kind of end-of-line thing it wants to represent. Besides, there are many
codepaths that want to use their own local "char *eol" variable to point
at the end of the current line they are processing.

This global variable holds what we read from core.eol configuration
variable. Name it as such.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

cache.h

@@ -606,7 +606,7 @@ enum eol {
 #endif
 };
 
-extern enum eol eol;
+extern enum eol core_eol;
 
 enum branch_track {
 	BRANCH_TRACK_UNSPECIFIED = -1,

config.c

@@ -583,7 +583,7 @@ static int git_default_core_config(const char *var, const char *value)
 
 	if (!strcmp(var, "core.autocrlf")) {
 		if (value && !strcasecmp(value, "input")) {
-			if (eol == EOL_CRLF)
+			if (core_eol == EOL_CRLF)
 				return error("core.autocrlf=input conflicts with core.eol=crlf");
 			auto_crlf = AUTO_CRLF_INPUT;
 			return 0;
@@ -603,14 +603,14 @@ static int git_default_core_config(const char *var, const char *value)
 
 	if (!strcmp(var, "core.eol")) {
 		if (value && !strcasecmp(value, "lf"))
-			eol = EOL_LF;
+			core_eol = EOL_LF;
 		else if (value && !strcasecmp(value, "crlf"))
-			eol = EOL_CRLF;
+			core_eol = EOL_CRLF;
 		else if (value && !strcasecmp(value, "native"))
-			eol = EOL_NATIVE;
+			core_eol = EOL_NATIVE;
 		else
-			eol = EOL_UNSET;
-		if (eol == EOL_CRLF && auto_crlf == AUTO_CRLF_INPUT)
+			core_eol = EOL_UNSET;
+		if (core_eol == EOL_CRLF && auto_crlf == AUTO_CRLF_INPUT)
 			return error("core.autocrlf=input conflicts with core.eol=crlf");
 		return 0;
 	}

convert.c

@@ -113,10 +113,10 @@ static enum eol determine_output_conversion(enum action action)
 			return EOL_CRLF;
 		else if (auto_crlf == AUTO_CRLF_INPUT)
 			return EOL_LF;
-		else if (eol == EOL_UNSET)
+		else if (core_eol == EOL_UNSET)
 			return EOL_NATIVE;
 	}
-	return eol;
+	return core_eol;
 }
 
 static void check_safe_crlf(const char *path, enum action action,

environment.c

@@ -43,7 +43,7 @@ const char *askpass_program;
 const char *excludes_file;
 enum auto_crlf auto_crlf = AUTO_CRLF_FALSE;
 int read_replace_refs = 1;
-enum eol eol = EOL_UNSET;
+enum eol core_eol = EOL_UNSET;
 enum safe_crlf safe_crlf = SAFE_CRLF_WARN;
 unsigned whitespace_rule_cfg = WS_DEFAULT_RULE;
 enum branch_track git_branch_track = BRANCH_TRACK_REMOTE;