mingw: avoid over-specifying --pic-executable

In bf2d5d8 (Don't let ld strip relocations, 2016-01-16) (picked from
git-for-windows@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.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

config.mak.uname

@@ -750,15 +750,15 @@ ifeq ($(uname_S),MINGW)
         ifeq (MINGW32,$(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 \