Added a comment with an alternate idea to avoid the backslash line contination character.

# ./lib/Makefile.inc

# Using the backslash as line continuation character might be problematic

# with some make flavours, as Watcom's wmake showed us already. If we

# ever want to change this in a portable manner then we should consider

# this idea (posted to the libcurl list by Adam Kellas):

# CSRC1 = file1.c file2.c file3.c

# CSRC2 = file4.c file5.c file6.c

# CSOURCES = $(CSRC1) $(CSRC2)

CSOURCES = file.c timeval.c base64.c hostip.c progress.c formdata.c	\

  cookie.c http.c sendf.c ftp.c url.c dict.c if2ip.c speedcheck.c	\

# ./src/Makefile.inc

# Using the backslash as line continuation character might be problematic

# with some make flavours, as Watcom's wmake showed us already. If we

# ever want to change this in a portable manner then we should consider

# this idea (posted to the libcurl list by Adam Kellas):

# CSRC1 = file1.c file2.c file3.c

# CSRC2 = file4.c file5.c file6.c

# CSOURCES = $(CSRC1) $(CSRC2)

# libcurl has sources that provide functions named curlx_* that aren't part of

# the official API, but we re-use the code here to avoid duplication.

curl_SOURCES = $(CURL_SOURCES) $(CURLX_ONES) $(CURL_HFILES)