mingw: avoid over-specifying `--pic-executable`

In bf2d5d8239e (Don't let ld strip relocations, 2016-01-16) (picked from
https://github.com/git-for-windows/git/pull/612/commits/6a237925bf10),
Git for Windows introduced the `-Wl,-pic-executable` flag, specifying
the exact entry point via `-e`. This required discerning between i686
and x86_64 code because the former required the symbol to be prefixed
with an underscore, the latter did not.

As per https://sourceware.org/bugzilla/show_bug.cgi?id=10865, the
specified symbols are already the default, though.

So let's drop the overly-specific definition.

Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.mak.uname

diff --git a/config.mak.uname b/config.mak.uname
index b667c69..f6387f4 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -757,15 +757,15 @@
         ifeq (MINGW32,$(MSYSTEM))
 		prefix = /mingw32
 		HOST_CPU = i686
-		BASIC_LDFLAGS += -Wl,--pic-executable,-e,_mainCRTStartup -Wl,--large-address-aware
+		BASIC_LDFLAGS += -Wl,--pic-executable -Wl,--large-address-aware
         else ifeq (MINGW64,$(MSYSTEM))
 		prefix = /mingw64
 		HOST_CPU = x86_64
-		BASIC_LDFLAGS += -Wl,--pic-executable,-e,mainCRTStartup
+		BASIC_LDFLAGS += -Wl,--pic-executable
         else ifeq (CLANGARM64,$(MSYSTEM))
 		prefix = /clangarm64
 		HOST_CPU = aarch64
-		BASIC_LDFLAGS += -Wl,--pic-executable,-e,mainCRTStartup
+		BASIC_LDFLAGS += -Wl,--pic-executable
         else
         endif
 	COMPAT_CFLAGS += -D__USE_MINGW_ANSI_STDIO=0 -DDETECT_MSYS_TTY \